UV disinfection for well water
If a lab test found coliform or E. coli in your well, a UV system is the most common long-term fix. It disinfects every gallon without chemicals, as long as the water reaching it is clear. Here's how it works, when it's the right call and what it costs installed.
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How UV works
Water flows through a stainless chamber around a UV lamp in a quartz glass sleeve. The UV light inactivates bacteria, viruses and parasites as they pass, with nothing added to the water.
No chemicals, no taste. UV doesn't change taste or smell.
No residual. It treats water only inside the unit, so the plumbing is disinfected at install.
Doesn't remove chemicals. CDC notes UV systems don't remove chemicals; nitrate, lead or PFAS need reverse osmosis or other treatment.
Fix the well first
Penn State Extension recommends starting with the well itself after a positive bacteria test.
Shock chlorinate. A strong chlorine dose disinfects the well and plumbing. Bacteria in well water →
Check the cap and casing. Penn State says about 15% of wells with coliform can be fixed by shock chlorinating and installing a sanitary well cap.
Retest. If bacteria come back, continuous disinfection such as UV is the next step.
What UV needs to work
Water quality decides whether UV works. The Water Quality Association notes water that looks crystal clear can still block UV light.
| Factor | Why it matters | Usual fix |
|---|---|---|
| Sediment and cloudiness | Particles shade bacteria from the light | Sediment prefilter ahead of the UV |
| Hardness, iron, manganese | They coat the quartz sleeve and cut the dose | Softener or iron filter ahead of the UV |
| Very high bacteria | Penn State: not recommended above 1,000 total coliform or 100 fecal coliform per 100 mL | Fix the source; consider chlorination |
| Lamp age | Intensity drops over time | Replace the lamp about once a year |
| Certification | Class A (40 mJ/cm²) is designed for water of unknown quality and includes a sensor and alarm | Ask which NSF/ANSI 55 class a unit is certified to |
What UV disinfection costs
UV goes last in line, after any softener or filter, so it sees clear water.
| System | Price, installed | With financing* |
|---|---|---|
| UV disinfection | $1,395 | about $30/mo |
| Water softener + UV disinfection | $3,690 | about $78/mo |
| Acid neutralizer + UV disinfection | $3,690 | about $78/mo |
| Iron filter + UV disinfection | $4,290 | about $91/mo |
| Iron filter + softener + UV disinfection | $6,585 | about $140/mo |
*60 months at 9.99% APR, subject to credit approval. Prices installed, as of October 2026.
How it works
Request your instant free quote
Fill out the free quote form or call (610) 400-3132. Tell us your address and whether you're on city water or a well.
We quote you on the spot
You get a clear price for your system right then, starting from a base package at a set price.
A free water test confirms your setup
Before we install, we test your actual water for free so you only pay for the treatment your water needs.
We install your system
We install it cleanly, show you how it works, and let you know when filters and service are due.
UV disinfection: common questions
What does a UV system do for well water?
It disinfects. Water passes a UV lamp inside a quartz sleeve, and the light inactivates bacteria, viruses and parasites without adding any chemical. CDC notes UV doesn't remove chemicals, so it's paired with other treatment when needed.
Do I need UV if my well tested positive for coliform?
Not always first. Penn State Extension recommends shock chlorinating the well and fixing the well cap, and says about 15% of wells with coliform can be treated that way. If bacteria come back, a continuous disinfection system such as UV is the next step.
When is UV not a good fit?
Penn State Extension says UV units aren't recommended where total coliform exceeds 1,000 colonies per 100 mL or fecal coliform exceeds 100 per 100 mL. UV also needs clear water: iron, manganese, hardness and cloudiness coat the sleeve or shade the bacteria.
What is NSF/ANSI 55 Class A?
A certification for UV systems. Class A systems deliver a dose of at least 40 mJ/cm², are designed for water of unknown quality and must include a UV sensor and alarm. Class B systems deliver 16 mJ/cm² and are for supplemental treatment of water already considered safe.
How much maintenance does UV need?
Replace the lamp about once a year, keep the quartz sleeve clean, and change the sediment prefilter. Penn State Extension puts electricity at about $2 to $4 a month.
Does UV keep the plumbing free of bacteria?
No. UV treats water only as it passes through the unit and leaves no residual disinfectant in the pipes. That's why the plumbing should be disinfected when the system is installed.
How much does UV disinfection cost?
UV disinfection installed by Willow Springs is $1,395, about $30 a month with approved financing. With a water softener it's $3,690, and with an acid neutralizer it's also $3,690.
Written by Sam Beiler, co-founder of Willow Springs Water Company, Sinking Spring, PA. Last updated October 2026.