Ultraviolet on a well that runs continuously is straightforward. On a property used a few weekends a year it is a different proposition, because the failure modes of an idle system are not the failure modes of a running one, and the household arrives, turns the water on and uses it within minutes of the lamp being energised.
What happens while it sits
Water standing in the pipework downstream of the lamp is unprotected, because ultraviolet leaves no residual, and a warm dead leg over a summer is a place where growth can establish. Sediment settles in filter housings and in the chamber. The quartz sleeve can develop deposits from standing mineral water. And in a property that is drained down for winter, the sleeve and lamp may be exposed to freezing, which cracks quartz. None of this is visible when the system is switched on again.
The arrival routine
Energise the lamp and give it time to reach full output before drawing water, which the manufacturer will state and which is longer than most people wait. Then flush thoroughly: run every tap, hot and cold, for several minutes to move the standing water out of the plumbing rather than drinking it. Check the controller for faults, and look at the pretreatment filters, which may have been sitting wet for months. Only then treat the water as treated, and consider bottled water for drinking on the first day of a long absence.
Setting it up to survive absence
Leave the system powered where the property is heated and secure, so the lamp is at full output whenever water moves, rather than switching it off at the consumer unit to save a small amount of electricity. Where the property is drained down, drain the chamber as the manufacturer directs and remove the lamp and sleeve if freezing is possible. Fit a shut off solenoid that closes the supply on lamp failure, which matters more here than anywhere: nobody is present to notice an alarm.
Testing on a schedule that suits the use
The EPA notes that private wells are not federally regulated under the Safe Drinking Water Act, and a USGS study of 2,100 private wells found about one in five carried at least one contaminant above a human-health benchmark, so testing is the owner's responsibility and it matters most where the system is unattended. Test at the start of each season rather than annually on a calendar, and after any flooding or work on the well. Our iron filter guide covers the pretreatment that keeps the sleeve clean.
Questions people ask about uv light filter for well water
Can I switch the UV system off between visits?
Where the property is heated and secure, leaving it powered is better, so the lamp is at full output whenever water moves.
What should I do on arrival?
Let the lamp reach full output, then flush every tap for several minutes to move standing water out of the plumbing before using it.
Is freezing a risk to the system?
Yes. A frozen chamber can crack the quartz sleeve, so drain as the manufacturer directs and remove the lamp and sleeve where freezing is possible.
How often should the water be tested?
At the start of each season rather than on a calendar, and after any flooding or work on the well.