Bacteria, viruses, and other pathogens are extremely dangerous to human health but can not be determined visually by looking at water, as they are relatively small. To be absolutely sure of bacteriologically clean water should bacteriological water analysis. The bacteriological water pollution is more common in surface water (rivers, lakes, ponds, open wells) and the centralized water supply networks.
UV light can efficiently reduce microbiological growth in water. UV radiation with a wavelength of 254 nanometers kills bacteria, viruses, algae, and fungi by destroying the DNA of the microorganisms. Disinfection by UV light is applicable to almost all water types.
The UV systems are developed and produced with a view to high efficiency, great reliability of operation, easy installation, long life, and minimum maintenance.
Another solution to reduce microbiological growth in water is dosing of biocides or chlorine chemical like NaClO (Natrium hypichlorite).