Water can be contaminated by
1. Disease-producing bacteria, viruses, and parasites especially those that come from human faeces.
2. Parasites with a circle through snails or cyclops, for example bilharzia and guinea-worm.
3. Chemicals that are poisonous, some coming from factories or farms.
Water also breeds the vectors of malaria and onchocerciasis.
Sources of Water
1. Surface water, for example dams.2. Springs.
3. Wells–shallow; deep; artesian.
4. Rivers.
5. Rainwater.
Knowing The Hardness of Water
This is due to excess salts of calcium and magnesium dissolved from the rocks through which water has passed. It can be removed by boiling, adding chemicals such as washing soda, adding excessive amount of soap, or the Permutit chemical softener.Disadvantages of Hard Waters. It is wasteful with soap. It furs kettles, boilers, and sterilizers, and so wastes fuel.
Protection of Water Supplies
1. Protection of Spring Water
Consult an health inspector about the suitability of the spring. Obtain the interest and assistance of the people who use the spring. Collect stones, obtain cement. Dig a trench 1 foot below the eye of the spring. Lay stones along the trench, and put a yard pipe in position. Cover the stoned water channel with reeds, earth, and grass. Make steps and a path at the side of the spring. Keep in good repair.
2. Protection Of Dams or Ponds
Experts should be consulted for construction. On occasion they may become dangerous breeding sites for mosquitoes or snails, and the health inspector should check these periodically.
3. Protection of Wells
These should be lined with waterproof material. They should have a concrete top and cover. They should have a pump with a water-tight joint or a bucket and chain. They should be fenced around. They should be chlorinated for 12 hours periodically if there is any chance of contamination.
4. Protection of Rivers
The cleanest water flows in the middle of the river. The river can be fenced off into different areas for washing, for obtaining water, and for animals.
The water in a river is usually contaminated with the excreta of animals and people, but fish, insects, plants, and sunlight help to purify it, and if it is a big river the germs are diluted.
5. Protection of Rainwater
This is collected from the roofs of houses into tanks, if the roof is made of either tiles, slates, corrugated iron. The water is safer if it is run into a special tank made of metal or with bricks, and well concreted. Once a year the tank should be scrubbed with chloride of lime. Rainwater tanks should be covered so that mosquitoes do not breed in them.
Purification of Water
This is done in many ways.Boiling
All water except that from a water-works should be boiled before drinking. This kills the organisms, and makes the water soft for washing.Distillation
Steam Collected, cooled, and condensed back into water, leaving the salts behind.Domestic Filter
The wave is filtered through a hollow candle of special matrieal. This must be scrubbed and boiled every few days.Natural or Self-purification–Storage
Water is stored in large tanks, and the following happens:1. The solids settle–a process called sedimentation.
2. Bacteria break up substances in solution.
3. Water-plants use up carbon dioxide and give out oxygen.
4. Sunlight destroys bacteria.
5. Storage gets rid of germs. Even typhoid organisms will die.
