Reference information

Term descriptions

Area of sanitary control is a certain area, where specific regime established, meant for the protection of centralized water supply and water-treating facilities from contamination.

Water disinfection is processing the water to remove pathogenic and sanitary indicator microorganisms.

Residual active chlorine is an indicator that the chlorination process is complete. It appears as chlorine is bound by the substances and bacteria found in the water. It guarantees the effectiveness of water disinfection. It is an indirect indicator of water safety when there is a threat of an epidemic; it is necessary to prevent a secondary water contamination in the distribution network.

Chlorine ABSORPTION of water is the amount of chlorine that can oxidize organic and easily oxidized inorganic substances and disinfect bacteria in 1 L of water within 30 minutes. This value is established experimentally by trial chlorination.

Chlorine DEMAND OF water is the total amount of chlorine necessary to provide for chlorine saturation and for the presence of residual active chlorine (0.3—0.5 mg/L ).

The primary objective of sanitary control regimen is sanitary protection of water sources and water supply systems as well as the locations they are found in from contamination.

Sanitary control areas are organized as three belts:

1. The first belt (area of strict control) includes the location of water intake systems, water works sites and water supply canal. This is intended for protection of these sites from casual or intended contamination or damage.

2. The second and third belts (restricted area) include the territory used for prevention of contamination of water sources and waterworks as well as the territory they are located on. the second belt is intended for protection from microbial contamination, the third – from chemical contamination.

Factors determining the boundaries of sanitary control area belts:

- type of water source (above ground or underground)

- nature of contamination (microbial or chemical),

- extent of natural protection against surface contamination (for an underground water source).

First belt boundaries for an underground water source: at a distance of 30-50 m or more from the water intake structure; for an above-ground source (rivers, canals)): upstream – 200 m or more from the water intake structure, downstream –100 m or more from the water intake structure, along the adjacent bank –100 m or more.

Second and third belt boundaries are determined with hydrodynamic calculations.