What is UV disinfection?

UV radiation of wavelenghts between 200 to 280 nm (UV-C) has proved to damage DNA molecules of most pathogenic micro-organisms including bacteria, viruses,yeasts, protozoa, fungi, cysts, spores, etc. The microrganism with damaged DNA loses its ability to cause infections.

No pathogenic micro organism is known to resist correctly applied and sufficient dose of UV-C radiation.

Why Disfect with UV?


Realiable protection from most water-borne diseases. Proven worldwide


Non-chemical, no disifection by-produsts


Cost-copetitive compared to chlorination-de-chlorination,Ozone and membrane filtration

UV dose

UV dose = Intensity of UV-C radiation x Exposure Time
[J/M 2]     [W/m2]     [seconds]

UV Dose is expressed as
Joules/m2 [J/M2] or as micro-Watt-Second/cm2[W-S/cm2]

300 J/m2 = 30 mJ/cm2 = 30 mW-S/cm2 w-s/cm2

How much UV dose is required?

  • The UV dose required to achieve 90% reduction of a specific micro-organism is called D 10 i.e. the dose at which only 10% of the micro-organisms surive.
  • Doubling the D10 UV dose achieves 99% reduction in the specific micro-organism.
  • D10 figures are known for most-organisms.*

UV dose required to achiveve various % reductions in E-Coli is shown below.

E-Coli – Relationship between UV dose and reduction as % of inlet count

Reduction %Reductions UV dose[mWS/CM2]
1/D10 90% 5.4mWs/cm2
2/D10 99% 10.8mWs/cm2
3/D10 99.9% 16.2mWs/cm2
4/D10 99.99% 21.6mWs/cm2
5/D10 99.999% 27.0mWs/cm2

*Please Contact us for UV dose required for reduction of a specific micro-organism for your application.

Simple regular maintenance (e.g. periodic replacement of UV lamps, cleaning/replacement of quartz sleeves) is recommended to maintain sufficient UV dose.