Frequently Asked Questions
Water Quality & Tap Water
The water that we drink in Gauteng comes from the upper Vaal River catchment which includes parts of Mpumalanga and the Free State Provinces. The rivers forming part of this catchment include the Vaal, Klein Vaal and Waterval rivers in Mpumalanga and the Klip, Wilge, Nuwejaarsspruit, Liebenbergsvlei and Ash rivers in the Free State. The Vaal is the main river in the catchment and all of the above mentioned tributaries enter it along the upper catchment.
The Vaal River has been dammed close its confluence with the Wilge River, its major tributary from the Free State. This is the Vaal Dam, which stores all the water from the upper Vaal River catchment. Rand Water has an intake tower close to the dam wall and from here raw water is pumped to the purification stations in Vereeniging and at Zuikerbosch.
There are two projects that involve the inter-basin transfer of water regarding our water that we drink in Gauteng. The inter-basin transfer of water means that water is transferred from one river catchment to another using pipes and pumps.
Two water transfer schemes have been built to move water from other catchments to the Vaal Dam catchment in order to meet the demands of the growing Witwatersrand. These schemes include the following:
1. The Thukela-Vaal Water Transfer Scheme
This scheme is found in the Drakensberg and was completed in 1974. The Thukela River starts at Mont Aux Sources, in the Drakensberg, and naturally flows through KwaZulu-Natal into the Indian Ocean. With the construction of the Thukela-Vaal Water Transfer Scheme, a certain amount of the water from the Thukela River is transferred via canals, pipelines and dams into the Vaal River system.
The Thukela River flows into the Woodstock Dam (Surface Area: 29 square kilometres; Average Depth: 40 metres; Total Storage Capacity: 380 million cubic metres) and then into the Driel Barrage further downstream. A certain amount of water is pumped from the Driel Barrage into a canal which then flows via gravity into the Kilburn Dam. Water from the Kilburn Dam is then pumped underground, over the Drakensberg (500m), and into the Driekloof Dam.
This section of the scheme is used to generate electricity as a hydroelectric power station has been built within the mountains of the Drakensberg. This power station, known as the Drakensberg Pumped Storage Scheme, is managed by Eskom and electricity that is produced here is fed into the national electricity grid. At peak periods (morning & afternoon) when electricity is need, water is dropped from the Driekloof Dam, through the underground hydroelectric turbines, and into the Kilburn Dam. In quiet periods the water is pumped back from the Kilburn Dam and into the Driekloof Dam. When the Driekloof Dam is full water flows over a weir and into the Sterkfontein Dam, where it is stored. The Sterkfontein Dam has a surface area of 67 square kilometres, an average depth of 93 metres, and a total storage capacity of 2,62 billion cubic metres.
When water is needed in the Vaal River system, water is released from the Sterkfontein Dam into the Nuwejaarspruit River, which then flows into the Wilge River and then into the Vaal Dam. As part of the future plans for water management in South Africa the building of two further dams are planned for the scheme, i.e. Mielietuin Dam (30 million cubic metres) on the Bushman’s River and Jana Dam (1500 million cubic metres) on the Thukela River which will have 121 km of pipelines that feed into the existing scheme.
2. The Lesotho Highlands Water Project
This scheme is found in the mountains of Lesotho. The mountains of Lesotho receive a great deal of water, in the form of rain and snow. Phase 1A of the project included the building of Katse Dam on the Malibamatso River. The Malibamatso River flows naturally into the Senqu River and then into the Orange River. Water from the Katse Dam (Surface Area: 37,6 square kilometres; Average Depth: 180 metres; Total Storage Capacity: 1,95 billion cubic metres) is drawn into a tunnel via an intake tower that is situated upstream of the Katse Dam wall. The water travels along an underground pipe, 44,75 kilometres long, through the Muela Hydroelectric Power Station and into the Muela Dam.
Here the water moves straight through the underground hydroelectric turbines to produce electricity for Lesotho. The water from the Muela Dam then travels along a 33,27 kilometre long underground pipe and finally flows into the Ash River, near Clarens in South Africa. The Ash River then flows into the Saulspoort Dam. Thereafter the water flows into the Liebenbergsvlei River, the Wilge River and then into the Vaal Dam. Phase 1A of this project was completed in 1998. Phase 1B saw the building of the Mohale Dam as well as an underground transfer tunnel that leads into the Katse Dam. Phase 2 includes the building of a further 3 dams in Lesotho, namely the Polihali Dam, the Taung Dam and the Lebelo Dam, with underground pipelines feeding into the existing dams. Plans for the Polihali Dam are underway with construction starting in 2011 and completion in 2019, at an estimated cost of R7.3 billion.
Water is a transport medium, as it carries along many substances from one place to another, just like a train. Water is made up of 2 hydrogen atoms and 1 oxygen atom (H2O). When a lot of these H2Os join together they form water. When water falls on the earth’s surface from the clouds, a lot of substances dissolve in the water, eg. silt, minerals, bacteria, etc., just like a train picking up passengers. Water is the train that moves along the tracks and the ‘passengers’ are these substances that get on and off the train. By the time water enters the dams it has many ‘passengers’, both good and bad to humans. There is silt and minerals from the land. There are germs (viruses & bacteria) that may cause people to get sick if they enter the human body. It is for this reason that the dirty water needs to be cleaned before it is supplied to taps. This cleaning process is called water purification. Rand Water is the company that cleans (purifies) the dirty water and then distributes it to mines, industries and local authorities. The local authorities supply this water to individual homes, businesses and schools in Gauteng and parts of Mpumalanga, Limpopo, North West and Free State Provinces. But how is tap water cleaned?
Where does our water come from?
Rand Water draws raw water for purification (cleaning) from the Vaal Dam from the Vaal Dam (Department of Water and Environmental Affairs) via an intake tower. This raw water contains some ‘passengers’ that can make it unsafe to drink. The raw water is transported through canals and pipelines to Rand Water’s purification stations in Vereeniging, where it is cleaned.
What is Screening?
When raw water arrives at purification station it passes through metal screens. These trap large living organisms (fish, crabs, floating plants, etc.), sticks, leaves & litter, but allow the water to pass through it.
What is Coagulation?
The raw water enters the middle of a spiral flocculator where slaked lime is added. This is thoroughly mixed in the rapidly moving water. The slaked lime attracts sand, silt and clay particles, some small living organisms, germs and all the ‘bad guys’ (pesticides, lead, mercury, arsenic, etc.) to form 'clumps'.
What is Flocculation?
As the water begins to slow down in the outer section of the flocculator, the ‘clumps’ join together to form ‘floc’.
What is Sedimentation?
The water flows slowly into large sedimentation tanks. The ‘floc’ then settles to the bottom of the tank to form ‘sludge’. This is called sedimentation. The ‘sludge’ is sucked up by desludging bridges and sent to a sludge deposit site. The water in the top part of the tank is now cleaner. It flows over the side of the sedimentation tank into the carbonation tank.
What is Carbonation?
When water leaves the sedimentation tank it has a pH of about 10.5, from the slaked lime that was added. This high pH (alkaline) makes the water feel and taste soapy. In order to make the water less alkaline (a lower pH), carbon dioxide is bubbled through the water. The pH of the water is now between 8.0 and 8.4. This makes the water taste and feel much better. At this pH level calcium carbonate is deposited in the distribution. This protects them from rusting.
What is Filtration?
The pH of the water has now been corrected through carbonation, but it still contains some small living organisms and germs. It flows into closed filter houses where it passes through sand filters. These are big, flat beds made up of different sized particles of sand and stone. As the water flows slowly through these filters all the small living organisms and some germs are trapped by the sand. The water now enters underground pipes.
What is Chlorination?
Even after the water has been filtered it still contains some germs. To kill these germs, chlorine gas (a disinfectant) is mixed with the water.
What happens to the clean water?
This clean water is pumped through underground pipes to booster pumping stations. The chlorine is only effective for 6 - 8 hours so it is necessary to add chloramine (chlorine & ammonia) to prevent any other germs, that may get into the water, from growing or multiplying. From the booster pumping stations the water is pumped into reservoirs. Rand Water then sells it to various local authorities that supply homes, schools, businesses and factories with clean water.
4. What different methods can be used to purify raw water at home in areas that do not have a municipal water supply?
Where there is a concern about the quality of drinking water in an emergency situation (or in rural areas where there is no adequate water sanitation) that cannot be addressed through central services, then the appropriateness of household treatment should be evaluated including for example:
- Bringing the water to a rolling boil and cooling before consumption.
- Adding sodium or calcium hypochlorite, such as your house hold bleach, to a bucket of water (1 teaspoon in 25l), mixing thoroughly and allowing to stand for at least 30 minutes prior to consumption. Turbid water should be clarified by settling and / or filtration before disinfection.
- Vigorously shaking small volumes of water in a clean, transparent container, such as soft drink bottle, for 20seconds and exposing the container to sunlight for at least 6 hours.
- Applying products such as chlorine tablets or other dosing techniques to disinfect the water.
Emergency decontamination processes may not always accomplish the level of disinfection recommended under optimal conditions, particularly with regard to resistant pathogens. However, implementation of emergency procedures may reduce numbers of pathogens to levels at which the risk of waterborne disease is largely controlled.
The parameters most commonly measured to assess the microbiological safety are as follows:
- E coli colonies per 100ml of water – more than 10 colonies of E. coli per 100ml of water indicates that there is a risk of bacterial infection if the water is consumed. Water with more than about 120 colonies per 100ml of water.
- Residual chlorine: Taste does not give a reliable indication of chlorine concentration.
- pH: it is necessary to know the pH of water, because more alkaline water requires a longer contact time or a higher residual chlorine concentration at the end of the contact time for adequate disinfection (0.4-0.5mg/litre at pH 6-8, rising to 0.6mg/litre at pH 8-9, chlorination may be infective above a pH of 10)
- Turbidity adversely affects efficiency of disinfection. Turbidity is also measured to determine what type and level of treatment are needed. Testing for turbidity can be carried out with a simple turbidity tube that allows a direct reading in nephelometric turbidity units (NTU).
Heavy metals are pollutants that can enter the drinking water system when they seep through soils into groundwater. Arsenic, cadmium and lead are just a few of the heavy metals in the environment at unsafe levels. Heavy metal pollution is usually the result of untreated mine waste but can also result from other industrial processes including the manufacturing and use of pesticides and fertilisers.
Atomic spectrometry converts each metal in the water sample to a particulate emission that can then be weighed. Extrapolations are made to determine each metal concentration in each water sample taken. The complicated analysis requires preserving the sample with acid, heating the sample to convert to a particulate emission and then identifying each metal and its weight.
A simple analogy is to capture the steam from a pot of water, separate every atom in the steam, identify each atom, weigh each atom and then apply these numbers back to the original volume of water contained in the pot. The result is an accurate picture of what is in the water.
Heavy Metals in Water
High heavy metals concentrations can be naturally occurring. Every geologic formation contains a certain amount of heavy metal. Mine operations extract and process these metals in areas with the highest concentrations. Water in these areas may have high metal concentrations due to the combination of naturally occurring deposits and mine waste. Water samples are usually taken randomly within a contaminated area and offsite to identify the source of contamination and the pathway it travels, into the drinkable groundwater system or away from potable water sources. Accurate determination of heavy metal contamination is important to identify cumulative risks to people drinking water derived from these areas.
Treating Heavy Metal Contamination in Water
Heavy metal water contamination is a difficult expensive problem to address. Most cleanup activities use a pump and treat system where contaminated groundwater is pumped out of the ground, treated with activated carbon to remove contaminants and then replaced into the groundwater system. Because large volumes of water must be pumped and treated over long time periods, associated operation and maintenance systems are very expensive. There are some new technologies being developed that actually treat the water in the ground which operate more efficiently and quickly, decreasing costs.
If groundwater is contaminated with heavy metals, an alternative source of drinking water must be used to prevent harmful health effects, until the water is treated to meet standards protective of human health and the environment.
Stand a glass of the water on a surface and watch it closely. If the white colour clears from the bottom up, it is caused by very small bubbles of air. The air is usually dissolved in the water under high pressure but when you open the tap, the pressure is released and the air bubbles to the surface. This is much like when you open a fizzy cooldrink! This is a totally harmless phenomenon.
Stand a glass of the water on a surface and observe it closely. If the water clears from the top down and a white substance settles out on the bottom of the glass, there may an excess of some type of mineral or chemical (such as calcium or zinc) in the water.
This should not normally happen in a well-regulated water supply system. Depending on what the substance is, it may or may not be harmful, but it does indicate a problem that must be attended to by your local authority or water provider.
The pipes leading to your home or the pipes in your home may be rusting. Your geyser may also be rusting. The rust collects in the pipes when water is not being used and is then flushed out when you open the tap.
Rust is basically iron oxide, a reddish brown substance formed when iron metal is exposed to water and air. Apart from causing discoloration of the water, iron oxide can stain laundry and impart a metallic taste to the water.
Caution: Acute poisoning in babies and children can occur after exposure to massive amounts of iron. A chronic form of poisoning called haemochromotosis can develop after years of regular intake of high iron concentrations.
Iron may be dissolved in the water. When it is exposed to air as you open the tap, it turns a reddish brown colour. The main effects of elevated iron concentrations are discolouration of the water, staining of laundry and a metallic taste. Iron is an essential nutrient for the human body and should not cause health problems at the concentrations normally found in drinking water supplies.
Your water may contain harmless brown substances called humic compounds. These come from decomposing plant matter. They are picked up as river water flows over leaves and roots of plants (similar to the way water changes colour when tealeaves are added to it!). This phenomenon is prevalent in the Eastern and Western Cape areas where humic substances come from the fynbos vegetation.
These substances are totally harmless. They may however cause staining of laundry. There is currently a debate amongst scientists as to whether humic compounds may be involved in the formation of chlorine disinfection by-products.
A muddy appearance could be due to soil or sand that entered the pipes supplying your home during a pipeburst, repairs or maintenance operations. Sometimes microorganisms grow around the particles of soil and these microorganisms may pose a health threat.
Allow the water to run until it clears. Use the muddy water to water your plants. If the problem persists, contact your local authority or water provider to check the pipes and flush them out if necessary.
A disinfectant-like smell or taste (like that found in public swimming pools) is caused by a substance called chlorine. Chlorine is added to drinking water as a disinfectant to kill microorganisms, particularly those that could cause waterborne diseases.
When chlorine is used for disinfection, it can react with other substances in the water to form disinfection by-products (DBPs). Animal research involving high levels of DBPs found increased formation of cancer, however the reason for this is not known. Research into the relationship between DBPs, cancer and other health risks is ongoing.
Chlorine has been used as a disinfectant since the late nineteenth century and has virtually wiped out instances of waterborne diseases like typhoid fever, cholera and dysentery in those areas where it is used.
The risks of epidemics of waterborne diseases in the absence of chlorinaton far outweigh the risks associated with the possible cancer causing effects of chlorination by-products. However, obviously everything possible should be done to minimise both risks.
An earthy or musty taste or odour is usually caused by a harmless substance called geosmin. Algae (tiny water plants) in rivers and dams produce this at certain times of the year, usually during summer months. The substance is harmless, but it does have a strong smell that the human nose is very sensitive to. You could detect 1 teaspoonful of geosmin in 200 Olympic sized swimming pools!
A rotten egg smell or taste comes from sulphur-containing substances formed by various types of bacteria and fungi. These organisms can be present in certain rivers and dams and some (sulphur reducing bacteria) can be found in some water supply pipes where they can cause corrosion of the inside surface of the pipe. The smell is probably due to a gas called hydrogen sulphide (H2S). The human nose can detect very low levels of this gas. Most often a faint smell of rotten eggs does not indicate levels that would be harmful. However, high levels of this gas is toxic and should not be inhaled. If you notice a sudden strong smell of rotten eggs in your drinking water, close the tap and evacuate the room. Go outside and breathe in lots of fresh air. Inform your local authority or water provider immediately.
A mineral taste (salty or bitter or metallic) can be caused by a variety of dissolved mineral salts in the water. These minerals occur naturally and come from the rocks, soils and vegetation that water flows over or through. Some are also introduced to drinking water when it is purified. The levels of minerals in drinking water varies from area to area. Minerals are important for maintaining a healthy body. However they should be consumed in the correct amounts. If your intake is too low this could lead to deficiency illnesses. If you consume too much this could also lead to illness. For example too little calcium leads to problems with bones, but too much calcium can contribute to kidney stone formation in sensitive individuals. In a well-regulated supply, the levels of minerals in the water should not be harmful.
The hardness of water refers to the sum of the concentrations of two harmless minerals: calcium and magnesium. The greater the concentration of these minerals, the harder the water. The hardness of drinking water around South Africa varies depending on the rocks and soils of the area that the water comes from, and the treatment process used by the water provider.
Hard water is healthy to drink because it provides high levels of minerals, but can cause other problems. It forms scums and is difficult to lather making washing difficult. It can also form scale deposits in pipes and hot water appliances like kettles. Hard water may also change the taste of water, especially for brewing tea and coffee.
Soft water is better for washing, but has been linked to heart disease. It can also corrode pipes and appliances.
Sources of Hardness Minerals in your water
- Water is a good solvent and picks up impurities very easily. When water is combined with carbon dioxide to form very weak carbonic acid, an even better solvent results. As water moves through soil and rock, it dissolves very small amounts of minerals and holds them in solution. The degree of hardness becomes greater as the calcium and magnesium content increases and is related to the concentration of multivalent cations in the water.
- The hardness of your drinking water around South Africa varies depending on the rocks and soils of the area that the water comes from, and the treatment process used.
Potential health Effects
- Hard water is not a health hazard. In fact, the National Research Council (National Academy of Sciences) states that hard drinking water generally contributes a small amount towards total calcium and magnesium human dietary needs. They further state that in some instances, where dissolved calcium and magnesium are very high, water can be a major contributor of calcium and magnesium to the diet.
- Rand Water has not established drinking water guidelines for hardness because there are no known negative health effects associated with calcium and magnesium minerals in your drinking water.
Indications of hard water
- Excessive hardness in water interferes with almost every cleaning task from laundering and dishwashing to bathing and personal grooming. Dealing with hard water problems in the home can be a nuisance. The amount of hardness minerals in water affects the amount of soap and detergents necessary for cleaning. Soaps used in hard water combine with the minerals to form a sticky soap curd. Some synthetic detergents are less effective in hard water as the active ingredients are partially inactivated by hardness, even though it stays dissolved. Bathing with soap in hard water leaves a film of sticky soap curd on the skin. The film prevents removal of soil and bacteria.
- Excessive hardness in water may also change the taste of water, especially for brewing tea and coffee.
- Hard water also contributes to inefficient and costly operation of water using appliances. Heated hard water forms a scale of calcium and magnesium minerals that can contribute to the inefficient operation or failure of water –using appliances. Pipes can become clogged with scale that reduces water flow and ultimately requires pipe replacement.
Hardness of water is classified as follows:
|Hardness Range (mg/L CaCO3)||Description of Hardness|
Soft water is great for laundry, bathing, steam irons, and auto batteries, but definitely not for anything else. A soft water is aggressive at leaching metals and has been linked to heart diseases. If you are contemplating installing a softener (Home treatment device). There are serious questions you should ask; Who will test the effectiveness of the softener, how often will these tests be run; and how will your drinking water quality be affected?
Rand Water does not test any home water treatment device, including softeners, and does not recommend the use of particular devices.
Contact your local authority or water provider to find out the hardness of your drinking water supply.
Most South African water providers quote water hardness as mg/lCaCO3. Water with a level of calcium carbonate over 80-100mg/l is considered “hard”. Water with less than 100 mg/l CaCO3 is generally labeled “soft”.
Hardness can also be expressed in a number of ways including mg/l CaCO3, ppm CaCO3, mmol/l alkaline earth metals, German Degrees Hardness, or French Degrees Hardness.
Water in Rand Water’s area of supply ranges from 60 to 110 mg/lCaCO3, thus we have a moderately soft to slightly hard water.
Minerals such as calcium and magnesium that are dissolved in your drinking water tend to settle out when water is heated and evaporates. These minerals are white and accumulate in hot water devices such as kettles, steam irons and showerheads.
These deposits of minerals are harmless, but can affect the functioning of the appliance being utilised.
No, not yet. The fluoridation of drinking water is still a hotly debated topic in South Africa. Indeed this debate has been raging around the world since the 1950’s. Fluoride is currently added to certain drinking water supplies in the UK, US and Canada as a cost-effective way to prevent dental cavities. However, this practice has been rejected in 13 European Union countries.
The Department of Health and various medical and dental organisations are driving the campaign to have fluoride added to water supplies in South Africa.
However, some water supply organisations and directorates of the Department of Water Affairs and Forestry in South Africa have expressed caution about the concept as it is difficult to control fluoride levels when interbasin transfer schemes are involved, and because of the unknown medical and environmental impact. The Department of Agriculture is similarly opposed to fluoridation due to possible effects on crop growth. Fluoridation is also fiercely opposed by some groups who view it as mass medication and opposed to the individual’s right of choice.
Fluoride is an essential trace element of a normal diet. It occurs in water and food. As with many chemicals, fluoride can be helpful in certain amounts, but harmful if it exceeds certain levels.
Fluoride is needed in trace amounts during tooth formation to harden tooth enamel. It also protects teeth against cavities by increasing the resistance of tooth enamel to the acids produces by bacterial plaques. There is also some evidence that long term consumption of water borne fluoride may prevent the development of osteoporosis.
However, at high levels, fluoride is toxic and can lead to a range of harmful health effects. Dental fluorosis can occur where teeth become mottled and stained. Furthermore, long term high intakes of fluoride can damage the skeleton, causing brittle bones, fractures and crippling. It has also been suggested that excessive fluoride intake can cause heart, kidney, thyroid and immune system problems. Because fluoride accumulates in the body over time (even when the levels are low), it may be linked to cancer. However the World Health Organisation has not found any evidence to link fluoride and cancer in humans.
It is obviously impossible to give one definitive answer for a country as large as South Africa and with so many different sources of drinking water and treatment processes. However if the water supply meets the latest South African Bureau of Standards specifications for drinking water quality, which are in line with World Health Organisation standards the water should be safe. The water supplies of most of the large towns and cities in South Africa do meet these specifications, and it is usually only the smaller water supply systems that have problems in this regard.
Water can basically be harmful in two ways. Firstly it can pose the threat of disease due to the presence of pathogenic (disease-causing) organisms in the water. Secondly it can hold a risk of chemical-related illnesses due to the presence of dissolved substance in the water. In areas with a well-developed water supply and sanitation system, where drinking water is properly disinfected and wastewater (sewage) is effectively removed and treated, water related diseases are rare. Fortunately, the chemical substances that are naturally dissolved in water normally occur at concentrations that are very low and therefore should not pose a health threat. However there are some chemicals used in agriculture, industry and the home that find their way into water sources and occur at levels that are potentially harmful.
Ask your local authority or water provider about the specifications that they use as guidelines for treating your drinking water. Find out how often they test the quality of the drinking water supply and if you can get the results of these tests. If you have concerns that can’t be resolved at the local level, the Department of Water Affairs and Forestry (DWAF) is the authority responsible for water related issues in the country.
In a properly managed drinking water system, disease-causing organisms (called pathogens or germs) should not be present in your drinking water. A water purification process is designed to remove large numbers of germs through processes such as filtration. Furthermore, to ensure that drinking water quality specifications are met, a final disinfection step is used in which chlorine or other disinfectants such as ozone or ultra-violet light are used to destroy any remaining germs.
There are many diseases caused by waterborne germs. These include, amongst others, cholera, typhoid fever, infectious hepatitis, dysentery, diarrhoea, gastro-enteritis, cryptosporidiosis, giardiasis, and bilharzia. These conditions can be very serious. Most germs should be destroyed during the disinfection stage of water purification however a few are difficult to destroy using conventional treatment. Monitoring occurs at all stages of the water purification and supply to ensure that the levels of these germs do not occur at high enough levels to cause disease.
Remember that illnesses like stomach upsets can be contracted by routes other than water, including air, food and contact with sick people. Any illness should be thoroughly checked by a doctor. The doctor will be able to make a correct diagnosis of the cause of the illness and prescribe appropriate treatment. If a waterborne illness is confirmed, inform your local authority or water provider and follow up on their actions to ensure a safe water supply.
This is a personal decision. Home treatment devices are not needed to make the water safe if it meets drinking water specifications. In fact if the devices are not properly maintained, they can actually promote water quality and health problems. You only need to consider buying a home treatment system are if you have a medical condition that makes you sensitive to components in drinking water or if taste is very important to you. You may also want to use one as an alternative to using an unregulated water supply such as a borehole or rain tank.
There are many types of home treatment systems available. Some are jug filters and some are in-line or point of use devices. Each type is designed to remove specific substances from water. It is crucial that you select the right system for your needs, and that you correctly maintain the system to avoid health risks such as bacterial build-up.
Particulate filters remove turbidity, colour, particles, specific inorganic compounds (eg. iron, aluminium and manganese) and some microorganisms. A disadvantage of these devices is that bacteria may grow on the filters and contaminate drinking water.
Adsorption filters contain some form of activated carbon which absorb tastes and odours, pesticides, decaying organic matter, dissolved gases, chlorine and chlorine by-products, some turbidity, suspended solids and organic substances. By removing chlorine from the water, however the growth of bacteria may be encouraged.
Reverse osmosis units will remove to varying degrees dissolved inorganics like sodium, calcium, nitrates and flouride. Organic contaminants such as pesticides and solvents are also removed. There are several drawbacks to reverse osmosis systems: the incoming water must be of a good quality, the membrane must be chemically cleaned and replaced regularly, flow rate is very slow and the treated water is often soft and acidic making it unhealthy to drink. Additionally for every one volume of water produced by the system, three volumes are wasted as “reject” water.
Ion exchange units do not purify water really, but they do remove nitrates and soften water by removing calcium and magnesium as well as mercury and iron. It is not healthy to drink water that is too soft, and it should only be used for washing.
Water softeners remove hardness but care should be taken to avoid over softening drinking water because it can cause high blood pressure.
Distillation units remove some organic and inorganic substances (hardness, and nitrates). Some organic chemicals pass through the unit with the steam and contaminate the “distilled water”. Distilled water has a flat taste and is missing many of the minerals that are found in regular drinking water. These minerals may be beneficial for your health.
There is currently no controlling body that regulates home treatment devices in South Africa. Some home treatment device companies use aggressive scare tactics to market their products. Some salespersons use dramatic visual demonstrations and make claims that are totally incorrect and unfounded.
It is important that you get the correct facts about the quality of you drinking water before you make any decisions which could cost you a lot of money, and even cause water quality problems.
Irritations of the skin are rarely caused by chemicals in the water, but by frequent contact with drinking water itself. Over washing or repeated contact and immersion in water can cause the skin to become chapped as it loses its natural oils and lipids. This can lead to a variety of skin problems.
The loss of the skin’s natural oils and lipids makes it more vulnerable to minor irritants that would not usually irritate a “normal skin”. The skin may then develop inflammation called “dermatitis” or “eczema” which causes itching. This when scratched causes more inflammation setting up a vicious cycle. The skin would look dry and scaly, like parchment paper, with a rough texture and sometimes with red areas. In severe cases, weeping and oozing may result which may be complicated by secondary infection. At first you may only be aware of a dry chapped sensation, but this may progress to severe itching. The hands are often the first to be affected, but the lower legs, thighs and back are often also affected.
In urban areas where there is a regulated water supply system, the answer is “no”. You do not need to drink bottled water for health reasons. The only reasons you should choose bottled water is if you prefer the taste, or if you have a medical condition for which your doctor has prescribed a specific bottled water. For example, if you are on a very restrictive sodium diet, your doctor may prescribe a certain bottled water has a lower sodium content than your tap water.
In South Africa, the bottled water industry is presently not well controlled with strict specifications concerning water quality and health standards and testing and monitoring.
Bottled water, like any water is prone to contamination by disease causing microorganisms if it is not properly disinfected. Bottled water is only disinfected at source and does not contain a long lasting disinfectant. With no residual disinfectant present, microorganisms are free to grow and multiply in the water once it leaves the source. As a result, it has been shown that microorganisms grow in the bottles after bottling and while they stand on shop shelves. You therefore put yourself at risk of a potential waterborne disease by consuming bottled water that could be contaminated.
Sensitive groups of people such as children, the elderly and people with immune disorders should be aware of all the risks involved in bottled water.
If you have a piped supply of water from a regulated water provider, there most probably is chlorine in your drinking water. Chlorine has been used as a disinfectant since the late nineteenth century and has virtually wiped out instances of waterborne diseases like typhoid fever, cholera and dysentery in those areas where it is used. It is currently the most commonly used disinfectant in water treatment processes worldwide. It kills the microorganisms (including disease-causing germs) that are present in the water. In South Africa enough chlorine is added to drinking water to ensure that the disinfectant effect lasts right up to your tap. This practice helps prevent any growth of microorganisms in the network of pipes and reservoirs between the treatment plant and your home. Although no specifications have been set for chlorine levels in South African drinking water, the residual chlorine levels at your home should be in the range of 0.2 and 1.5 milligrams of chlorine per litre.
The greatest health risk arises when there is not enough chlorine in your water. With no chlorine present, microorganisms can multiply and cause disease.
Unusually high levels of chlorine can cause a disinfectant type taste and odour (similar to a public swimming pool). Chlorine can also react with other substances in the water to form disinfection by-products (DBPs). Animal research involving high levels of DBPs found increased formation of cancer, however the reason for this is not known. Research into the relationship between DBPs, cancer and other health risks is ongoing.
The risks of epidemics of waterborne diseases in the absence of chlorinaton far outweigh the risks associated with the possible cancer causing effects of chlorination by-products. However, obviously everything possible should be done to minimise both risks.
Other ways of disinfecting drinking water are with ozone, ultraviolet radiation and membrane filters. These are expensive and do not provide a residual disinfectant effect along the water distribution network. Continuous research is being done around the world to find new disinfection methods.
A common type of “worm” that sometimes finds its way into drinking water supplies are Chironimid larvae. Theses are slender elongated cylindrical organisms that are pink to deep red in colour. These organisms are commonly known as blood worms (due to their colour). They are the larval stage of the midge insect. The adult midge resembles small mosquitoes and lay eggs in water which later hatch into the larvae. The larvae then pupate and emerge as adults from the water.
Chironimid larvae are harmless and swallowing one would be as harmless as swallowing an ant. However, it is obviously not aesthetically acceptable to have them in drinking water.
Contact your local authority or water provider and get them to correctly identify the organism. Find out where the organisms entered your water supply system and make sure you rectify the problem and prevent it from happening again.
Possible points of entry include the tap itself, an overhead tank, storage reservoirs or at treatment plants.
Until the problem is resolved, you could boil and strain the water if you wish.
Yes, absolutely. Water that has been treated to a standard fit for human consumption, it is more than adequately safe to use for plants. South Africa is an exception to many parts of the world, where drinking water would never be wasted on plants. In certain countries, there is a separate system for drinking water and water for other uses such as washing and gardening.
There should be no negative effects on plants, on the contrary they should be very healthy if all their other needs such as nutrients, drainage, light, temperature, pest and disease control are taken care of.
Water your garden and plants with tap water and watch them flourish. But remember that water is a scarce resource in South Africa, so you should not waste it. Practice “Water Wise” gardening methods such as selecting indigenous plants with low water requirements, grouping plants according to their water needs, watering in the cool of the day, using a watering can where possible, mulching and container gardening.
To determine whether municipal water is “better” than municipal water you need to consider aspects of health, aesthetics and economics. You need to investigate which type of supply best suits your needs, situation and the use to which you want to put the water.
Groundwater is water that occurs underground in certain layers of rock. Groundwater is abstracted from water-bearing or water-saturated layers of rock via boreholes and wells. There are many different types of wells and boreholes of varying depths and dug by different methods (including dug, borred, driven, jetted or drilled). Boreholes are smaller and deeper then wells. Water enters boreholes by flowing sideways through the holes of a perforated steel shaft. Water enters wells by flowing upwards from the bottom of the well.
There is a common perception that groundwater is pure and not affected by pollution or contamination. In many instances in South Africa this is true and groundwater meets SABS drinking water specifications. However, groundwater quality varies greatly from area to area and just like surface water (rivers and dams) is affected by the activities in the area (eg. agriculture, industry, sewage systems) as water pollutants and contaminants can move from the surface into the ground and reach the groundwater.
Groundwater and surface water may both be polluted in different ways. Surface waters can be contaminated by municipal sewage, industrial discharge and transportation accidents and rainfall runoff. It therefore can contain many different pollutants, but not in very high quantities. Groundwater, on the other hand, may contain pollutants such as arsenic, nitrates, radioactive materials, and high amounts (compared to surface waters) of a few organic chemicals such as cleaning fluid. The degree of pollution in surface waters can change rapidly, while pollution levels in groundwater change very slowly.
Note that if the groundwater does not meet drinking water specifications, it may still be suitable for other uses like irrigation, washing or bathing.
You are responsible for maintaining your borehole system, and for monitoring the groundwater quality. You also need to ensure that the water is not contaminated after it is abstracted from the ground, for instance in reservoirs or storage tanks.
You need to base you decision on facts. Have samples of your borehole water and municipal water tested by a reputable laboratory. Compare the water quality. Also compare the costs involved for each option. Select the one that best meets your specific needs. If you decide to use borehole water for drinking, remember to monitor its quality regularly.
A correct answer to this question requires a study of water quality analyses performed over time on your drinking water. It is however highly unlikely that there has been an overall deterioration of drinking water quality. Ongoing research and improvements in water treatment technology world-wide results in continually improving processes and monitoring systems. Contrary to the pervasive belief amongst certain urban populations, drinking water quality has actually improved in many parts of South Africa.
Legislation requires water providers and local authorities involved in drinking water supply to adhere to specifications set by the South African Bureau of Standards (SABS). The SABS specifications are based in international guidelines for drinking water quality.
A deterioration of the quality of drinking water supplies would rapidly manifest itself in massive outbreaks of diseases and illness, especially in sensitive groups of people.
Ask your local authority or water provider for records of water analyses taken over the years in which you have perceived a change in water quality.
You could even have independent tests conducted on your drinking water by a reputable laboratory to put your mind thoroughly at ease.
Study these facts to determine if there has really been a deterioration in water quality. If there has been a deterioration, you must bring this to the attention of local authority or water provider if they don’t already know. Apply pressure to ensure that steps are taken to improve water quality or at least stop any further decline. These steps may include improved protection of source waters, changes in the treatment process, improved monitoring and the protection and maintenance of the distribution system.
Both the chemical and microbiological content of water will vary from area to area based on where the water comes from and how it is treated at the purification plant.
The chemical content of water refers to type an level of dissolved substances such as minerals, gases, metal salts, chemicals and organic compounds that may be present in water. These may occur naturally, or may be due to pollution. Some chemicals in water are added during purification to make it suitable for drinking. There are routine tests used to evaluate the levels of important compounds in drinking water.
The microbiological content refers to the type and number of microorganisms present in the water. These microorganisms may be algae, fungi, bacteria, viruses, protozoa and worm or insect larvae. Usually, water is tested for the presence of faecal coliforms or E.coli, which are bacteria present in the digestive systems of humans and animals. If these are present it indicates that the water may be contaminated by human or animal wastes.
This will vary from area to area. Water quality is first determined by the catchment or water basin that the rivers and dams are situated in. It is influenced by the rocks, soils, vegetation and the human activities taking place in the catchment. Water quality is then also affected by the treatment process used to purify it for drinking. It is important to understand that water purification aims to remove harmful or offensive substances form the water to make it safe and pleasant to drink in a cost effective way. The aim is not to load the water with additional substances, although certain chemicals are needed to make the water drinkable.
Legislation in South Africa requires that all water providers and local authorities ensure that drinking water complies with SABS specifications for drinking water, which are based on international guidelines.
The chemical and microbiological content of drinking water is routinely monitored. Ask your local authority or your local water provider for results of chemical and microbiological analyses performed on the drinking water in your area. Also ask for an interpretation of the results so that you can understand the data.
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