1.4. Sources of water supply
1.4.1. Requirements to the water quality.
Water quality is evaluated by composition and qualities, after what determined its suitability for one or another aims. Especially strict conditions are applied to water, which is used for economically-drinkable needs of consumers of production, settlement and civic buildings. This water should meet requirements of ГОСТ 2874-82 “Drinkable water”. Norming of concentrations of one or another substance is conditioned by necessity of providing of favorable organoleptic qualities of drinkable water, harmless of its chemical composition and safety of the water in sanitary relation. Non-conformity of even one of these norms to requirements of ГОСТ 2874-82 gives base for determination of unfitness of the water for drinkable aims.
There is determined limited indication of harm – organoleptic or sanitary-toxicological – for all normed substances. For example, iron in the water even in great concentration (more than 0,3 mg/l) hasn’t toxic influence on human’s organism, but give to water yellow-brown color, deteriorates its taste, causes development of iron bacterium and putting of sediment on plumbing. Limited indication of harm for iron combinations is organoleptic. The same is concerned to manganese. Inversely, such chemical substances, as combinations of strontium, nitrates are toxic for human, but don’t change organoleptic water properties. For example, strontium with concentrations more than 7 mg/l oppresses the activity of much ferment. At the same time, bitter taste water got only when concentration of the strontium is more than 12 mg/l. For such a combinations limited indication is sanitary-toxic.
Content in the water more than 500 mg/lof sulfates or 350 mg/l of chlorides gives to water salty taste and causes breaking of activity and sickness of human stomach. This water has bigger corrosion activity, higher non-carbonate stiffness, destructively acts of reinforced-concrete constructions.
Materially influences on human’s health fluorine, iodine, bromine, boron etc. So, lack or surplus of fluorine in the drinkable water causes destruction of teeth and changes in the skeleton, lack or absence of iodine leads to man’s illness on endemic goiter (ендемічний зоб) etc. Poisoning action on human and warm-blooded animal organism have salts of heavy metals and radioactive elements.
Cations of calcium and magnesium conditioned water stiffness. Though they don’t causes especial harm to organism, their presence in the water in a big amount is unwanted, because such water is little of use for economical needs. In stiff water increases consumption of washing tools and soap during clothes washing, slowly boil meat and vegetables. Stiff water is unfit for systems of inverse and heat water-supply, for steam coppers and usage in many branches of industry. Siliceous acid is not harm for health, but increased content in water makes such water unfit for feeding of steam coppers because of appearance of silicate scale.
Sanitary safe for drinking is water, in which total content of bacterium per 1 mi doesn’t exceed 100, and amount of bacterium of intestinal bacillus group per 1l – not more than 3.
According to organoleptic indexes drinkable water should have turbines not more than 1,6 mg/l, colorists not more than 20 degrees of platinum-cobalt scale, taste and smell not more than 2 points. Drinkable water shouldn’t have film on its surface and contain water organisms, which can be determined by unaided eye. Allowable contain of chemical substances, mg/l, which influence on organoleptic indexes: dry rest – 1000, chlorides- 350, sulfates – 500, manganese – 0,1, copper – 1,0, zinc-5, polyphosphates – 3,5, iron – 0,3, aluminum – 0,5.
Total stiffness of drinkable water should be not more 7 мгЧекв/л, hydrogen index pH – 6-9. For plumbing, which gives water without any special adaptation, according to sanitary-epidemical department is allowed total stiffness 10 мгЧекв/л, dry rest 1500 mg/l, iron content up to 1 mg/l, manganese up to 0,5 mg/l.
Harmless chemical composition of water is provided while the concentration toxic chemical substances not more than, mg/l: beryl – 0,0002, molybdenum – 0,25, arsenic – 0,05, nitrates – 45, polyacrylamide – 2, plumb – 0,03, selenium – 0,01, strontium – 7, fluoride – 1,5 (for 1st and 2nd climatic regions) 1,2 (3rd), 0,7 (4th), uranium – 1,7. Containing of radium should not exceed 1,2 h 10-10 Ки/л, strontium – up to 4 h 10-10 Ки/л.
If there are some substances in the water (except fluoride, nitrates and radioactive materials) their concentration should correspond to the formula:
where C1, C2 … Cn – determined concentrates, mg/l, ГДК1, ГДК2 …ГДКn – installed limited-allowable norms.
Requirements to water on the industrial enterprises depend on type of industry and can be various. First of all, attention is paid to interaction of water with plumbing, equipment, raw materials and industrial production. If requirements to some technical water are not set by technologists, norm indexes should be evaluated according to exploitation of analogical enterprises or using “Enlarged norms of water consumption and water drainage for different industrial branches”.