Water Management Issues
Existing low cost technologies that can save lives today
- Adding chlorine in liquid or tablet form to drinking water stored in a protected container.
- At a dose of a few mg/l and contact times of about 30-60 minutes (one teaspoon of domestic bleach to 20 litres of water and leaving it for one hour). Free chlorine generally inactivates >99.99% of enteric bacteria and viruses, provided water is clear.
- Household chlorination has achieved widespread use, and is appropriate for on-site disinfection.
2. Solar disinfection
- One low cost technique involves exposing water in clear plastic bottles to sunlight for six hours e.g. on the roof of the house (or for 2 days if the sun is obscured by clouds). One can also paint the plastic bottle black.
- A combination of heat and ultra-violet radiation from the sun are used to inactivate pathogens present in water.
- The water should be consumed directly from the bottle or transferred to a clean glass.
- To be effective, solar disinfection must be applied to relatively clean water.
- Additional advantages include water taste being largely unchanged and minimal risk of re-contamination if water is consumed directly from the bottle in which it was treated.
- Solar disinfection is suited for very poor households in regions that draw relatively clear water.
- Water filtration is another way to purify water.
- High quality ceramic filters with small pores, often coated with silver remove bacterial growth as well as suspended solids.
- Filters need to be cleaned regularly to maintain flow rates, and if properly maintained, they have a long life.
- Some commercial systems that combine filtration and disinfection are highly effective, though their upfront cost may be an obstacle to low-income populations.
4. Combined flocculation/disinfection systems
- Adding powders or tablets to coagulate and flocculate sediments in water followed by a timed release of chlorine.
- These typically treat 10-15 litres of water, and are particularly useful for treating turbid (murky) water.
- The water is normally stirred for a few minutes, strained to separate the flocculant, and allowed to stand for another half hour for complete disinfection.
- Households can disinfect their drinking water by bringing it to a rolling boil, which will kill pathogens (disease causing bacteria) effectively. This is the most common treatment approach.
- In order to be effective, however, the treated water must be protected from re-contamination.
- Caution must be exercised to avoid scalding accidents, especially among young children.
6. Safe Storage
- Water that is safe at a point of collection is often subject to faecal contamination during collection, transport and use in the home, mainly by unclean hands.
- Vessels with narrow mouths and taps can significantly reduce such contamination and reduce the risk of diarrhoeal disease.
- Safe storage should also be included in interventions to treat the water in the home.
- Ensure that the containers that are used in the home for storing drinking water are clean and that they are properly covered to ensure that flies and dirt do not settle into the water in the container.
Additional Management Issues to combat Waterborne Diseases
In the management of water quality for domestic purposes it is important to bear in mind that the achievement of safe water for drinking and food preparation rests with the management of safety of the water supply along the whole water supply chain. The water supply chain consists of the water source, treatment works, distribution system, the supply tap, the drinking water container, jug or cup.
- In the case of the repair of a burst pipe where dirt may gain access to a supply line which may result in a temporary increase in the microbiological total plate count in this supply line, the consumer will be alerted to the problem by brown water coming out of the tap. The situation is usually solved by flushing the pipe via the tap and allowing the contaminated water to flow down the drain.
- Rodents may gain access to gravity feed tanks on top of high rise-buildings, which may not be covered properly. Such tanks will need flushing and proper screening of any access points.
- Always ensure that the containers that are used in the home for storing drinking water are clean and that they are properly covered to ensure that flies and dirt do not settle into the water in the container.
- The general practice of personal hygiene is essential in limiting the spread of waterborne diseases. Children must be educated from a young age, with the adults setting an example to always wash their hands after going to the toilet. The use of soap is important as it helps to disinfect the skin of the hands, which may be microbiologically contaminated after using the toilet. Where running water is not available e.g. when camping or out in the field, then a small basin of clean water will also serve the purpose of making hand washing possible.
- Water for clothes washing must also be microbiologically clean, as some microorganisms can survive on the clothing after drying, and can be a source of infection either to an open wound to the skin, or via inhalation of dust breathed in through the nose.
- While prevention of waterborne diseases is the best approach to use, medical treatment is essential when a person is seriously ill with a disease.