Water sanitation

Water is a vital necessity of life without which man can live only for few days. About two thirds of our body weight is formed of water.

1. WATER SANITATION Dr. Dalia El- Shafei Ass.Prof of Occupational Medicine

2. Natural water Supplies

3. Small Scale purification: used in villages, small confined areas. It is used for water supply at the individual levels in case of absence of large-scale purification

4. Rural water supply

5. 1- River water : - A popular source where people go to the canal to fill utensils. They used for domestic purposes without purification and may be kept in porous containers (e.g. zeer , kolla ) for cooling purpose not for purification. Water is unsafe and thus can expose consumers to infection.

6. 2-Shallow wells: - Used by some houses for private water supply. - Shallow underground water, which is located in the superficial layers of the soil, is raised to the surface by a pump. Advantages : B acteriologically safe if sanitary measures are taken. Disadvantages : Exposed to pollution, from the surface & nearby sources (latrines, cesspits & refuse heaps) with the risk of spreading water-borne infection. P otential sources of pollution must be eliminated with an area of 20 meters radius all around the well. A shallow well is 1 st licensed after sending water sample for lab analysis & should be continuously licensed to ensure safety.

7. 3- Deep wells: Underground water in the deep layers is obtained by constructing a deep well at a depth of more than 20 meters to reach the deep underground water layer. Pumped water is raised up to fill a high tank reservoir of suitable size. Water is distributed from the tank to a number of public taps located at different spots of the village. Advantages : - Deep water is clear, but not tasty, it is hard (not forming foam with soap). - Bacteriologically sterile but pollution is possible through cracks or leakage through pipes. Disadvantages : In certain localities, deep underground water contains excess chemicals, from strata of earth, which may cause: *Dental fluorosis: Excess fluorine (>1.5 ppm) causes mottling of the enamel of teeth. * Methemoglobinaemia : Excess nitrates (>20 ppm) lead to the formation of nitrites which is absorbed, and affects Hb leading to a serious and fatal disease in infants.

8. Standards of potable water

9. Water examination for physical, chemical & bacteriological standards is carried out at each step of water purification.

10. Physical standards: Must be odorless, colorless, agreeable taste and clear. Presence of organic matter, algae, silt and mud can alter water's physical characteristics (becomes turbid, changes odor) but not necessarily cause harm .

11. Chemical standards: pH must be neutral or slightly alkaline. With a moderate degree of hardness. Hardness is the presence of insoluble salts of calcium & magnesium in water. It can cause GIT disturbance, waste of soap and explosion of boilers. It is removed by boiling, addition of lime or precipitation. Permissible hardness is 20 degrees. Safety limits for some chemicals are determined such as nitrate 1.0 ppm, fluoride 1.5 ppm, iron 0.3 ppm, arsenic & lead must be nil .

12. Bacteriological standards: - It concentrates on evidence of faecal pollution. - Water is inoculated on agar & other special media. - Coliform organisms are used as indicators for presence of bacteria. - A high coliform count of ≥ 100 ml is regarded as being suspicious of fecal pollution. - E . coli must be totally absent. No ova, no cysts or parasites.

13. Water pollution is any physical, biological & chemical changes in water quality that adversely affects living organisms (man, animal and fish) or make water unsuitable for desired uses

14. Water borne epidemic

15. - Sudden or explosive onset. - Large number of cases is reported in few days. - All cases having common water supply. - All ages, both sexes and different social groups are affected. - More than one case may be simultaneously found in same family. - May occur in any season. Cases of diarrhea & other GIT manifestations may appear before epidemic wave due to associated infection with other pathogenic organisms of shorter IP. When water supply is controlled cases drop suddenly but take time to return to the pre-epidemic level due to occurrence of 2ry cases.

16. Control of water borne epidemic: C ontrol of the water source that caused the epidemic. Increase the amount of chlorine added to the water & then neutralize the excess.