Drinking water

Drinking water ozonation is the standard method of disinfection in developed countries: the majority of tap water in Europe is treated with ozone. Ozone destroys bacteria, viruses, protozoan cysts and spores with very high efficiency (up to 99.99%) and is significantly more effective than chlorine, especially against chlorine-resistant pathogens such as Cryptosporidium.

Unlike chlorination, ozonation does not form carcinogenic byproducts such as trihalomethanes. It improves the taste and odor of water and reduces color. Residual ozone decays to oxygen within 20–30 minutes, leaving no chemical traces. Recommended residual ozone in drinking water at the consumer tap is 0.1–0.3 mg/L; systems must include proper contact time and, where required, degassing before distribution.

Important: Residual ozone in drinking water must not exceed 0.1–0.3 mg/L at the point of use. Ozonation equipment must be designed and operated in accordance with drinking water standards, with adequate contact time and degassing so that water supplied to the distribution network meets regulatory limits.

Water disinfection methods comparison

Parameter	Ozonation	Chlorination
Effectiveness against bacteria	99.99%	99.5%
Effectiveness against viruses	99.99%	90-95%
Effectiveness against cysts	99.9%	< 50%
Disinfection time	2-10 minutes	30-60 minutes
Byproducts	None (O₂)	Trihalomethanes (carcinogens)
Effect on taste	Improves	Chlorine smell
Effect on color	Reduces	No effect
Prolonged action	No	Yes

Ozonation technical parameters

Recommended parameters for drinking water
Parameter	Value	Regulatory document
Ozone dose	1-3 mg/L	Depending on water quality
Residual ozone	0.1-0.3 mg/L	Drinking water standards
Contact time	4-10 minutes	At temperature 10-20°C
Water pH	6.5-8.5	Optimal range
Water temperature	4-25°C	Effective range
Source water turbidity	< 2 NTU	Recommendation

Important: Ozone dose of 1-3 mg/L ensures complete water disinfection. At high organic load, the dose is increased to 5 mg/L for oxidation of organic compounds.

Ozonation process

Pre-treatment

Removal of mechanical impurities and suspended solids. Water turbidity should be < 2 NTU for effective ozonation.

Ozone generation

Production of ozone from purified air or oxygen by corona discharge method. Ozone concentration in gas: 8-12% (from oxygen) or 2-3% (from air).

Ozone dissolution

Mixing ozone-air mixture with water through ejector or bubbler. Dissolution efficiency: 85-95%.

Contact chamber

Water retention in contact chamber for 4-10 minutes to complete oxidation and disinfection reactions.

Degassing

Removal of residual ozone from water before supply to distribution network. Residual concentration: < 0.1 mg/L.

Post-chlorination (optional)

Addition of minimal chlorine dose (0.3-0.5 mg/L) for prolonged effect in distribution network.

What ozone destroys in drinking water

Bacteria: E.coli, salmonella, cholera vibrio, legionella — 99.99% in 2 minutes
Viruses: hepatitis A, rotaviruses, enteroviruses, noroviruses — 99.99% in 4 minutes
Protozoa: giardia, cryptosporidium (chlorine-resistant!) — 99.9% in 5 minutes
Bacterial spores: anthrax, clostridia — 99% in 10 minutes
Organic pollutants: phenols, pesticides, oil products — oxidation to CO₂ and H₂O
Iron and manganese: oxidation to insoluble forms for subsequent filtration

Disinfection effectiveness

Pathogen inactivation time (CT value, mg×min/L)
Pathogen	Ozone	Chlorine	UV (mJ/cm²)
E. coli	0.02	0.4	7
Poliovirus	0.3	1.7	30
Rotavirus	0.4	3.5	40
Giardia (cysts)	0.6	50	80
Cryptosporidium	3.0	> 7200	12

Ozone is especially effective against cryptosporidium — parasites causing diarrhea. They are practically resistant to chlorination (requires more than 7200 mg×min/L of chlorine for inactivation), but vulnerable to ozone.

Benefits of drinking water ozonation

Safety

Does not form carcinogenic byproducts. Decays to oxygen in 20-30 minutes.

Effectiveness

Destroys 99.99% of pathogens, including chlorine-resistant cryptosporidium.

Quality improvement

Eliminates unpleasant taste and odor, improves water color.

Regulatory compliance

Full compliance with drinking water standards and international standards.

Ozonation system productivity

Recommended equipment for water treatment
Station capacity	Ozonator power	Contact chamber
10 m³/h	20-30 g/h	1-2 m³
50 m³/h	100-150 g/h	5-10 m³
100 m³/h	200-300 g/h	10-20 m³
500 m³/h	1000-1500 g/h	50-100 m³
1000 m³/h	2000-3000 g/h	100-200 m³

Regulatory framework

Drinking water standards «Drinking water. Hygienic requirements for water quality»
Bottled water standards «Drinking water. Hygienic requirements for bottled water»
GOST R 51232-98 «Drinking water. General requirements for organization and quality control methods»
MUK 4.3.2030-05 «Control methods. Physical factors. Ozone and its hygienic regulation»
GN 2.1.5.1315-03 «Maximum permissible concentrations of chemicals in water bodies»