When a source of drinking centralized water supply is selected, priority is given to artesian (pressure) waters. They are reliably protected from contamination from the surface by rock formations. In the absence of such, they pass to others: pressureless horizons, groundwater. The analysis of water from the well is required, according to the results of which the quality of natural waters and their compliance with the regulatory requirements of drinking water are evaluated. It is possible to use the well for drinking water supply if there is a positive conclusion issued by the territorial body of the Rospotrebnadzor.
Sample selection
The reliability of the results of chemical and bacteriological research depends on which dishes and how the samples were taken, how soon after the sampling, water analysis from the well was performed.
It is preceded by sampling of water pumping from the well until the stream 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. Bacteriological properties of water should be determined within 24 hours after sampling.
For a chemical analysis of water from a well, samples are taken in a plastic container. Clean glass or plastic (new or mineral water) bottles are suitable. They are rinsed several times with selected water. Bottles are filled so that no air bubbles remain in the dishes. The volume of the sample depends on what kind of analysis will be carried out. For shortened, 1.5 liters is enough, for full - 3 liters.
For radiation analysis, water is poured in a slow stream through a hose lowered to the bottom of the bottle to avoid the escape of radon.
Dish for samples for bacteriological research will give laboratory SES. They will also instruct in the right way to take a sample. It is better if the laboratory assistant does it. Sample delivery time - no more than two hours. Analysis of water from the SES well is carried out immediately.
Qualitative indicators
Drinking water should be: with favorable organoleptic properties (that which a person perceives as sensory organs), harmless in its chemical composition, safe in radiation and bacteriological relations.
Drinking water is evaluated by its 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 serves as a guarantee of the absence of surface water inflow.
Odor and taste with a taste are also determined on site or no later than 2 hours from the time of selection. By origin, odors can be: natural (marsh, putrefactive, hydrogen sulfide, fish and others) or artificial (phenolic, camphor, chlorine, tar and others).
The best drinking water is odorless and tasteless. Water is allowed to be used when assessing taste and smell at 2 points.
The 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.
The color of water is the color caused by various substances (humic, tannin, colloids of iron). An indicator is allowed with a value of no more than 20 degrees, or up to 35, as agreed upon by the Chief Sanitary Doctor on 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 dependent on salinity.
Chemical indicators
Analysis of water from a well without fail includes the definition of:
- Active reaction (pH) - the degree of acidity or alkalinity, is determined quantitatively by the concentration of hydrogen ions. The limits of the indicator are 6.5-8.5.
- Alkalinity is the content of salts of organic acids.
- Total stiffness - 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 indicator should not be higher than 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 - a 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 are present, and especially nitrates, the water cleans itself. The pollution is old. For drinking purposes, the use of water with traces of ammonia and nitrites is permissible. Nitrate is allowed no more than 10 mg / l. The concentration of this contaminant in drinking water of 50 mg per liter disrupts the oxidative function of the blood.
- Oxidation (the amount of oxygen equivalent to the oxidizer consumption) for groundwater is characterized by a value of no higher than 5 mg / L O 2 .
- Hydrogen sulfide - in addition to the unpleasant smell of rotten eggs, it gives water corrosive activity, causes tube overgrowth due to the development of sulfur bacteria.
- Dissolved oxygen - at any time of the year at least 4 mg per liter.
- Iron (total content) - not more than 0.3 mg per liter of water.
- Sulphates - not more than 500, chlorides - not more than 350 mg per liter of water.
- Microcomponents (permissible values are given in mg per liter): arsenic - not more than 0.05; fluorine - not more than 1.5 for the I and II climatic regions and not more than 1.2 mg / l for the III climatic region; copper - not more than 1; zinc - less than 5; Manganese - not more than 0.1.
A complete analysis of well water contains other microcomponents: mercury, lead, strontium, cadmium, molybdenum, selenium, cyanides.
microbiological indicators
The total microbial number is not more than 50 colonies of microbes in 1 ml of sampled water. In 100 ml of the sample coliform common and thermotolerant bacteria should not be.
Radiation safety standards
For drinking water, the limit values of indicators are established (unit of measurement Bq / l):
- total alpha particle radioactivity 0.1;
- total beta particle radioactivity 1.0.
Other information
Responsibility for determining the hygienic standards of groundwater lies with the supplier, referred to in the 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 a list of analytes and the frequency with which water from the well is analyzed. Rospotrebnadzor has accredited laboratories in all cities of Russia. This federal institution monitors and supervises the quality of the supplied water. You can order the analysis to be performed in any other laboratory, but be surely accredited to perform the above analyzes. Before proceeding to a centralized drinking water supply, the water user must obtain the opinion of the chief territorial sanitary doctor on the analysis of water from the well. The price for determining one indicator is approximately 450 rubles.