Household Water Treatment and Safe Storage Factsheet: Source ...

Household Water Treatment and Safe Storage
Factsheet: Ultraviolet (UV) Disinfection Key Data
Inlet Water Criteria
Turbidity < 5 NTU (Nephelometric Turbidity Units)
Iron < 1 ppm (parts per million)
Treatment Efficiency
Bacteria Viruses Protozoa Helminths Turbidity Chemicals
Laboratory > 99.99% 0 > 99.99% 0 > 99.99% 0 > 99.9% 0 0% 0%
Field
97% to
0,3
100%
Not available Not available Not available 0% 0%
1 Cohn (2002)
2
Lang et al. (2006)
Gadgil et al. (1998)
Effectiveness depends on UV dose; these numbers are for NSF Standard 40 mW-s/cm 2
Required UV dose varies with water quality (e.g. turbidity, organic matter, pH)
Operating Criteria
Flow Rate Batch Volume Daily Water Supply
5 litres/minute 1 Not applicable 2,000 litres 1
1 Depends on the UV tube/apparatus design
Flow and volume depend on system design
Very turbid water should be sedimented or filtered prior to UV treatment
Robustness
Requires regular source of electricity, either through a grid or solar panels
Requires supply chain, market availability and regular purchase of UV bulbs
The design flow rate must be maintained by the user to ensure adequate UV dosing
If electricity is intermittent, water can be treated when electricity is available and stored
Estimated Lifespan
10+ years
UV bulbs should be replaced every 12 months (dirty or scratched bulbs reduce performance)
Manufacturing Requirements
Worldwide Producers:
Some companies make UV tubes for household water treatment (e.g. UV Waterworks, USA)
UV bulbs are available in various sizes from most major lamp manufacturers (e.g. General
Electric, Sylvania, Phillips)
Local Production:
Household UV treatment units can be manufactured from local materials provided adequate
knowledge and UV bulbs are available
Design will vary depending on local materials available
Materials:
Feed container
PVC tubing, or metal, pottery or cement channel
Stainless steel sheet metal