When a source of drinking centralized water supply is selected, priority is given to artesian (pressure) water. From pollution, they are reliably protected from the surface by water-resistant layers of rocks. In the absence of such, they move on to others: non-pressure horizons, groundwater. It is obligatory to analyze the water from the well, the results of which assess the quality of natural waters and their compliance with the regulatory requirements for drinking water. It is possible to use a well for drinking water supply if there is a positive conclusion issued by the territorial body of Rospotrebnadzor.
Sampling
The reliability of the results of a chemical and bacteriological study depends on what dishes and how the samples were taken, how soon after sampling the water from the well was analyzed.
Preceding sampling pumping outof water from the well until the jet is completely clarified and to a constant dynamic level. Chemical indicators must be determined no later than 72 hours. If this is not possible, then the sample is cooled and preserved (in the laboratory). The water of samples delivered later loses its properties, and the results of the analysis are always unreliable. The bacteriological properties of water must be determined within 24 hours after sampling.
For chemical analysis of water from the well, samples are taken in plastic containers. Clean glass or plastic (new or used mineral water) bottles are suitable. They are rinsed several times with selected water. The bottles are filled so that there are no air bubbles in the dishes. The volume of the sample depends on the analysis to be carried out. For a shortened one, 1.5 liters is enough, for a full one - 3 liters.
For radiation analysis, water is poured slowly through a hose lowered to the bottom of the bottle to avoid radon volatilization.
Dishes for samples for bacteriological research will be issued by the SES laboratory. They will also instruct you on how to properly take a sample. It is better if the laboratory assistant does it. Sample delivery time - no more than two hours. SES analyzes the water from the well immediately.
Quality indicators
Drinking water should be: with favorable organoleptic properties (what a person perceives with the senses), harmless in its chemical composition, safe in radiation and bacteriological terms. Drinking water is evaluated by physical, radiation, chemical and microbiological properties.
Physical properties
Water temperature is measured at the sampling site. The constancy of this indicator in different seasons of the year guarantees the absence of surface water inflow.
Smell and taste with aftertaste are also determined on the spot or no later than 2 hours from the moment of selection. By origin, odors can be: natural (swamp, putrefactive, hydrogen sulfide, fish, and others) or artificial (phenolic, camphor, chlorine, resin, and others).
The best drinking water is odorless and tasteless. Water is allowed for use with a score of 2 for taste and smell.
Transparency of water is associated with the presence of suspensions and colloids in it. The norm of this indicator for drinking water is 30 cm. If the transparency is less than 10 cm, then suspended particles are determined without fail.
Color of water is a color caused by various substances (humic, tannin, iron colloids). An indicator with a value of not more than 20 degrees is allowed, or up to 35 if agreed by the Chief Sanitary Doctor for the territory.
Turbidity of water, according to the standard, is acceptable at the level of 1.5 mg/l, but no more.
The electrical conductivity of water is directly related to salinity.
Chemical indicators
The analysis of water from the well necessarily includes the definition:
- Active reaction (pH) - the degree of acidity or alkalinity, quantified by the concentration of hydrogen ions. limitsindicator 6, 5-8, 5.
- Alkalinity - the content of s alts of organic acids.
- Total hardness - the total value of calcium and magnesium ions. For drinking purposes, the permissible concentration is not more than 7 mEq per liter.
- Dry residue - characterizes the presence of impurities. In drinking water, this figure should not exceed 1000 mg per liter.
- Nitrogen-containing substances - these include ammonia, nitrites (nitrous acid) and nitrates (nitric acid). They are "markers" of water pollution. If there is ammonia in the water, but no nitrites - fresh decomposition of protein compounds. Their joint presence indicates a certain period from the moment of primary pollution. If there is no ammonia, but nitrites and, especially, nitrates are present, the water is self-purifying. Pollution is old. For drinking purposes, it is permissible to use water with traces of ammonia and nitrites. Nitrates are allowed no more than 10 mg/l. The concentration of this pollutant in drinking water of 50 mg per liter disrupts the oxidative function of the blood.
- Oxidability (the amount of oxygen equivalent to the consumption of an oxidizing agent) for groundwater is characterized by a value not exceeding 5 mg/l O2.
- Hydrogen sulfide - in addition to the unpleasant smell of rotten eggs, it makes water corrosive, causes overgrowth of pipes due to the development of sulfur bacteria.
- Dissolved oxygen - at least 4 mg per liter at any time of the year.
- Iron (total content) - no more than 0.3 mg per liter of water.
- Sulfates - no more than 500, chlorides - no more than 350 mg per liter of water.
- Microcomponents (permissible valuesgiven in mg per liter): arsenic - no more than 0.05; fluorine - not more than 1.5 for I and II climatic regions and not more than 1.2 mg/l for III climatic region; copper - no more than 1; zinc - less than 5; manganese - no more than 0, 1.
A complete analysis of well water also contains other microcomponents: mercury, lead, strontium, cadmium, molybdenum, selenium, cyanides.
Microbiological indicators
Total microbial count - no more than 50 colonies of microbes in 1 ml of water being tested. Common coliform and thermotolerant bacteria should not be present in a 100 ml sample.
Radiation safety standards
For drinking water, limit values are set for indicators (unit Bq/l):
- total radioactivity of alpha particles 0, 1;
- total radioactivity of beta particles 1, 0.
Other details
Responsibility for determining groundwater hygiene standards rests with the supplier, referred to in Russian legislation as a water user. According to water legislation, he is obliged to license his activities, as well as obtain a license for the extraction of groundwater.
This document establishes the list of analyzed substances and the frequency with which the analysis of water from the well is carried out. Rospotrebnadzor has accredited laboratories in all cities of Russia. This federal institution controls and supervises the quality of the water supplied. Analysis can be orderedin any other laboratory, but necessarily accredited to perform the listed analyzes. Before proceeding to the centralized drinking water supply, the water user is obliged to obtain the conclusion of the chief territorial sanitary doctor for the analysis of water from the well. The price of determining one indicator is approximately 450 rubles.
