How is drinking water quality checked?

Drinking water should be safe for human health, taste good and odorless. The requirements for it in the Russian Federation are strict, they are regulated by sanitary rules and regulations, where all indicators of water quality are indicated.

Drinking water quality control

The quality control of tap drinking water is assigned to economic organizations that provide cold and hot water supply. Verification activities include the systematic sampling of water from the water supply system and laboratory analysis.

The frequency of monthly surveys is determined depending on the total number of the served population:

• up to 10 thousand people - twice;
• up to 20 thousand –10 times;
• up to 50 thousand - 30 times;
• up to 100 thousand - 100 times.

With an increase in the number of residents connected to one water supply network, the number of checks increases by one for every five thousand people.

In private houses that are not connected to a central supply system, water is taken from wells and boreholes. The owners of the premises themselves must control its quality in order to identify the amount of harmful impurities. It is possible to avoid health problems by conducting research twice a year - the composition of the water is constantly changing. Filtration systems reduce the risk of harmful elements entering food and drink.

Main factors

The quantitative and qualitative components of water from natural sources depend on the geographical and climatic conditions, the structure of the aquifers. To find out how safe a liquid is, it is examined according to certain criteria.

The main indicators for which checks are carried out: organoleptic, physicochemical and bacteriological.

The first category assumes an assessment of smell, color, taste, visual and weight determination of suspensions. In the latter case, the weight of impurities remaining after filtration of the sample is determined. The allowed value is 1.5 mg / l. The rest of the parameters are calculated based on the results of more complex laboratory tests.

Hydrochemical testing

Includes testing for hardness, acid-base balance (pH), oxidizability and concentration of dissolved salts.

The main indicators of the quality of drinking water in this category and their values ​​according to GOST:

• The pH value indicates the activity of hydroxide ions. If it is equal to seven, the water is considered neutral, decreases - acidic, increases - alkaline. The normal level ranges between six and nine.
• Hardness is determined depending on the concentration of calcium and magnesium ions in the water. Normally, it ranges from 7 to 10 mEq / l. Hardness values ​​of water from deep underground sources from 50 meters - from 8 to 10 mg-eq / l, and with water intake closer to the surface - from 3 to 6 mg-eq / l.
• Oxidation refers to the concentration of organic compounds dissolved in water. Increased values ​​indicate that the liquid is very contaminated with waste from the domestic sphere. Most often, oxidizability is determined by the permanganate method. The indicator should not be higher than 5 mg / l.
• Mineralization reveals the concentration of dissolved salts. Measurement is carried out on a dry residue. The limit of the salt content is 1000 mg / l. The optimal range of salt concentration is from 200 to 400 mg / l. The amount of calcium ions cannot fall below 25 mg / l, magnesium ions - 10 mg / l.

The temperature indicator at the catchment should be in the range from 7 to 12 degrees.If it is higher, there will be no refreshing effect. Water colder than five degrees is a health hazard due to the high chance of a cold.

Bacteriological examination

The results of the back analysis give out the concentration of the pathogenic microflora. Studies determine the microbial number - the number of microorganisms that are in 1 ml of liquid. For tap water, this value should not be more than a hundred. Artesian springs are the least contaminated with microorganisms. The microbial number there is no more than 30. Requirements for tap water according to SanPiN do not allow the presence of protozoa in it.

Fecal contamination is also determined by the concentration of E. coli in the water. It is measured in coli-titers and coli-indices. In the first case, the amount of liquid in milliliters containing one E. coli bacteria is detected. For drinking water, the coli-titer value should be 300 or more. If the index is calculated in the opposite way. The number of Escherichia coli, which are in 1 liter of drinking water - no more than three.

If toxic substances and radiation are suspected, toxicological and radiological studies will be required. The relevance of such analyzes is high if the sources of water intake are located near production facilities.

The quality of bottled water is determined by its class. It can be mined from deep or surface sources, purified tap water, conditioned. In any case, its data should not run counter to the values ​​of GOST, sanitary and hygienic standards.

Self-study of water

For these purposes, devices are used that detect harmful cock at home. But they are not cheap. In order not to spend money and at the same time be sure of safety, you can conduct tests using folk methods:

• Determination of the presence of salts and impurities. One drop of water is applied to a clean glass and allowed to dry completely. If the glass surface remains streak-free, the water can be considered clean.
• Identification of opportunistic microorganisms, organics and chemistry. A container with a volume of three liters is filled, closed with a lid and placed in a place protected from light for two or three days. The appearance of a greenish coating on the walls indicates the presence of microorganisms, the precipitate that falls - about an excess of organic matter, a film on the surface - about the presence of hazardous chemicals.
• Home Drinkability Testing. A weak solution of potassium permanganate is prepared, approximately 100 ml, and poured into a glass of water. The liquid should brighten. If a yellowish tint appears, you cannot drink such water.

Such tests will not be able to show all contamination; this requires large-scale research. If the liquid from the tap sharply smells of bleach or other chemistry, has acquired an unnatural shade and taste, oil spots appear on the surface or foreign impurities, a laboratory examination of tap water will be required. You can contact your local sanitary and epidemiological station.

Experts will make a sampling, conduct analyzes for toxicity and organoleptic properties, evaluate the liquid for chemical and microbiological indicators in accordance with generally accepted standards. Based on laboratory tests, they will recommend suitable filtration systems.

Water from the surface of the earth and from its bowels is used in the food, household, agricultural and industrial sectors. Quality indicators are regularly reviewed and measured. This is due to the increasing pollution of water sources from year to year. However, the requirements for drinking water remain unchanged. These are vital characteristics as water directly affects human health.