Sanitary requirements to quality of water
Quality of the water used by the population for economic-drinking needs, is characterised organolepticheskimi by properties, a chemical compound and absence or presence of pathogenic microorganisms.
Water, according to GOST 2874-82 ' Water drinking ', should meet following requirements: to be safe in the epidemic relation, harmless on a chemical compound and to have favorable organolepticheskie properties. This GOST regulates only quality of water water and consists of two parts. In the first part are stated, hygienic requirements to water and norms of its separate indicators, in the second - the control over quality of water. STATE THAT first part has three sections: the first - microbiological, the second - toxicological and the third - organolepticheskie water indicators.
Epidemic without pasnost waters characterise the microbiological indicators including the general number of microorganisms and number of bacteria of group of an intestinal stick. These indicators should not exceed norm.
The Number of microorganisms in 1 ml of water, according to STATE THAT, should not exceed 100. This norm has been offered for the first time in 1892 by Robert Kokh and has kept the force till now. This opening consisted in the following. Kokh studied cholera epidemic in Hamburg and has paid attention that in the nearby city of Altone of epidemic of a cholera was not. It has appeared, potable water clearing in this city is that, that after it in 1 ml of water the total of microorganisms did not exceed 100. Supervision have shown, that the less general number of microorganisms in water, the it is less probability of presence in it and activators of diseases.
The Second indicator normalises quantity of intestinal sticks in water. So, in 1 their l should not be more than 3. Rationing of quality of water on an intestinal stick is considered more perfect as the intestinal stick can get to water with vydelenijami the person and consequently, together with it can get and other activators of intestinal infections, i.e. The intestinal stick can signal about presence at water of other pathogenic microorganisms of intestinal group. The intestinal stick is the steadiest activator, and consequently if it in water do not find out in such water there will be no also other microorganisms - activators of diseases. For the first time rationing on this indicator (if-index) it was offered in 1936 on the basis of studying of experience of research of water of many waterpipes. In the early fifties S.N.Cherkinsky by whom admissible sizes of microbiological indicators of water have been entered was engaged in this question - if-titr and if-index. In the second section STATE THAT the toxic chemical substances characterising harmlessness of a chemical compound of water are normalised. And those indicators which meet in natural waters are normalised only or get to them in the course of processing.
The indicators testifying to hit in water of substances with sewage (they are normalised ' by Rules of protection of superficial waters from pollution ') are not normalised. On chemical substances, toksiches ki operating on an organism, potable water should correspond to requirements STATE THAT.
The Raised maintenance of aluminium (above 0,5 mg/l) influences taste of water. Normalised berilly - the substance possessing expressed toxic action on bodies of breath, cardiovascular and nervous systems, a liver. Meets in areas where there are deposits berillievyh ores (Argentina, Canada, Brazil). Toxic action on a human body renders in the quantity exceeding 0,0002 mg/l.
The Maintenance in molybdenum water should not exceed 0,25 mg/l. In areas with deposits molibdenovyh ores concentration of molybdenum in water can make about 1,2 mg/l. At the use of water with the raised concentration of molybdenum in a human body the gout develops, increase of the maintenance of uric acid in blood is marked.
Nitrates, - nitric acid salts - almost always meet in natural waters (soil and superficial) in which they arrive with rain waters (they can be formed during a thunder-storm of air nitrogen, at electric categories). Underground waters can contain a considerable quantity of nitrates at their big maintenance in soil. Nitrates cause vodno-nitratnuju metgemoglobi-nemiju, i.e. Toxic tsianoz.
In water the substances applied on a waterworks for water treating are normalised also. So, to improvement of process of coagulation apply synthetic polymeric connection - poliakrilamid (flokkuljant). After processing by this substance in water the residual quantity poliakrilamida which should not exceed 2 yokes/l can be found out.
At the lead Maintenance in water should not exceed 0,03 mg/l. Lead - poison of cumulative action. Arriving In an organism together with water, it collects and causes a poisoning. There is this substance in natural waters of those areas where there are deposits of connections of lead.
Selenium - the substance possessing expressed toxic and cumulative action, is slowly deduced from an organism. Water meets the big maintenance of selenium in Tuva ASSR, in Southern Urals Mountains. Its norm in water - no more than 0,001 mg/l.
The Maintenance of strontium not radioactive in water should not exceed 7 mg/l. This substance is washed away from breeds in which underground waters lie down. The raised maintenance of strontium in water promotes development urovskoj to illness, especially in the presence of a lack of calcium of an organism.
Fluorine meets almost in all natural waters of the USSR where it arrives from soil. The norm of fluorine is connected with a climatic zone. So, for I and II climatic areas the fluorine maintenance in water should not exceed 1,5 mg/l, for III area (Ukraine)-no more than 1,2 and for IV area (the country south, Central Asia, caucasus) - no more than 0,7 mg/l. That fluorine level in water corresponded optimum, water fluorinate.
In the third section STATE THAT are normalised organoleptiche-skie indicators of water which should be the following: a smell at temperature of air 20 °s and at heating to 60 °s - no more than 2 points; taste and smack at 20 °s - also no more than 2 points; chromaticity - no more than 20 °, mutnost - no more than 1,5 mg/l (on a standard scale). In coordination with bodies of sanitary-and-epidemiologic service the increase in chromaticity to 35 °, mutnosti (during the freshet period) - to 2 mg/l is supposed.
Hygienic value of a smell and smack of water consists that at their intensity more than 2 points are limited in-dopotreblenie. Artificial has begun to smell also smack testify to pollution of water by sewage, and natural - about occurrence in water of biologically active substances allocated with seaweed.
Hygienic value of chromaticity of water consists that it serves as an indicator of efficiency of decolouration of water on a waterworks, mutnosti - that at any turbidity of water it is considered suspicious in the sanitary relation.
Some chemical substances influence on or-ganolepticheskie properties of water. They can meet as a part of natural waters or be added to water in the course of its processing. STATE THAT second part concerns water quality assurance. It is laboratory-industrial inspection spent taking into account a local environment and it is co-ordinated with bodies of sanitary-and-epidemiologic service. Thus quality of water is checked before receipt in a distributive network on microbiological, chemical and or-ganolepticheskim to indicators. On waterpipes from superficial sources of water supply the water analysis is spent by forces sanepidsluzhby not less often than an once in a month, and from underground - within the first year of operation is not more rare than four times (on seasons of year) and is not more rare than an once in a year during the most adverse period (by results of supervision of the first year) further. If water at use of an underground source is not disinfected,
The microbiological analysis spend not less an once in a month at a population to 20 thousand people and not less than two times a month - to 50 thousand people If water is disinfected, this analysis spend once a week (the population to 20 thousand people), three times a week (the population to 50 thousand people) and daily at a population more than 50 thousand people
At disinfecting of water by chlorine or ozone is not more rare than an once at an o'clock define their residual concentration. The maintenance of free residual chlorine in water should make 0,3-0,5 mg/l, connected - 0,8-1,2 mg/l; concentration of residual ozone should be 0,1-0,3 mg/l (at maintenance of time of contact not less than 12 mines).
HYGIENIC REQUIREMENTS TO QUALITY OF WATER OF LOCAL SOURCES OF WATER SUPPLY
Quality of water of local sources of water supply, for example mine wells, is regulated ' by Sanitary rules on the device and the maintenance of wells and kaptazhej the springs used for decentralised economic-drinking water supply ' № 1226, confirmed MZ USSR of 20.02.75 Water of local sources of water supply is not exposed to such processing as the water of open reservoirs used for drink, and, hence, its sanitary estimation not always can be spent according to GOST 2874-82. Therefore for a hygienic estimation of quality of water of local sources of water supply recommend to use following rough specifications: a transparency - not less than 30 sm; chromaticity - no more than 40 °; a smell, smack - to 2-3 points; the general rigidity - to 14 mg-ekv/l (40 °); the fluorine maintenance - to 1,5 mg/l; nitrates - to 10 mg/l (in recalculation on nitrogen); chlorides - 20-30 mg/l; microbic number - to 300-400 in 1 ml; If titr - not less than 100, if an index - no more than 10.
Chromaticity of water is caused by natural features. For example, marsh water contains much guminovyh substances that reduces a transparency and increases its chromaticity. However it does not specify in danger of pollution of water. It is possible to judge it on such indicators, as oxidability, the maintenance ammonijnyh salts, nitrites, i.e. On chemical indicators of pollution. Oxidability of water of wells should not exceed 4 mg 0 2 in 1 l of water.
The Source of increase in the maintenance azotsoderzhashchih substances (ammonijnye salts, nitrites, nitrates) in water is decomposition of organic substances. Therefore concentration excess ammonijnyh salts, nitrites and nitrates, characteristic for water of the given district, specifies in pollution by its organic substances.
However not always this indicator testifies to organic pollution of water as in some districts ammonia can meet in faultlessly pure water as a product of the reactions proceeding in a mineral part of soil. For example, ammonia often meets in ferruterous waters. Besides, salts of nitric and nitrogenous acids can be restored to ammonia as a result of influence denitrifitsirujushchih the bacteria which are in soil or in water.
Hence, ammonia presence in water will be an indicator of pollution of water organic substances only when other indicators of pollution will testify to it, for example big okisljae-most also.
Ammonia is an initial product of rotting of organic substances and consequently its presence in water specifies in fresh pollution by its organic substances. At older pollution in water end-products of a mineralization of organic substances - nitrates will collect. Thus, on presence in water of ammonia, nitrites or nitrates it is possible to judge prescription of pollution of water. Besides, it gives the chance differentsirovanno to approach to an estimation of pollution of water. So, if ammonia presence in water at the repeated analysis does not prove to be true, it is possible to tell, that water more does not become soiled. If in water all three indicators (ammonia, nitrites and nitrates) it testifies to its regular pollution are simultaneously found out.
Therefore in water of local sources of water supply of salt of ammonia and nitrogenous acid are supposed in the form of traces (ammonijnye salts to 0,1 mg/l, nitrites to 0,002 mg/l), and nitrates - no more than 10 mg/l in recalculation on nitrogen.
Consumption of the well water rich with nitrates, causes in children of chest and preschool age heavy disease - metgenoglobinemiju.
The Maintenance of chlorides is usually equal in spring and well water 20-40 mg/l. Well water can contain a significant amount of chlorides in saline soil, but it will not serve as a pollution indicator; it.
The Principle of rationing of chlorides in such water is its flavouring suitability.
Chlorides can Sometimes serve as an indicator of pollution of water organic substances of an animal origin as excrements of the person and animals, especially urine, and also kitchen slops contain chloride sodium much. If in water simultaneously find out the raised maintenance of chlorides and ammonia it is possible to suspect, that it is polluted by urine.
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