Water Quality
Successful disinfection depends upon exposing water to a sufficient intensity of UV light for a sufficient amount of time. Water failing to meet certain general water quality guidelines may reduce the effectiveness of a UV system. For a UV system to work effectively, a 5-micron (nominal) filter must be present before the system. Many wells and surface water sources are already filtered. The filter assures that particles large enough to block UV light do not go through the system. If your water isn’t cloudy or smelly, you don’t have rust stains in your toilet, and you soften (or don’t need to soften!) your water, water quality should not be an issue for your UV system. If you believe you face any of these water quality problems, consult you local water treatment dealer and mention that TrojanUV offers free water testing for hardness, iron, UV transmittance (UVT) and turbidity. Water quality parameter | Maximum recommended level | Symptoms | Concern | Solution | Hardness | 120 ppm * 7 grains per gallon * | Difficulty getting soap to lather; mineral buildup on plumbing fixtures; mineral buildup in water lines and appliances. | Hard water minerals may accumulate on the lamp's protective quartz sleeve, preventing some of the UV light from getting into the water. | Water softener, or regular cleaning of the quartz sleeve. | Iron | 0.3 ppm ** 0.3 mg/l ** | Reddish or orange staining in toilets and on plumbing fixtures; rusty water color; sediment; metallic taste; reddish or black slime. | Iron may accumulate on the quartz sleeve that protects the UV lamp. Dissolved iron can absorb UV light and decrease the UV transmittance of the water (see below). | If in solid form, a filter is adequate. If dissolved, ask your local water treatment dealer about some of the following possible solutions: water softeners; oxidizing filters (manganese greensand or zeolite); aeration; chemical oxidation with potassium permanganate or chlorine; followed by filtration. | UV Transmittance (UVT) | 75% | Water may appear cloudy or coloured. | Besides iron, a few other compounds are also able to absorb UV light. This decreases the amount of light that reaches pathogens. | Consult your local water treatment dealer. | * The US Department of the Interior and the Water Quality Association consider that water above 120 ppm (7 gpg) is “hard”
** US EPA Secondary Drinking Water Regulation standard
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