Can I shock chlorinate my own well?

Many Pennsylvania owners do; Penn State Extension publishes the procedure, and the materials are inexpensive. Respect the details: correct chlorine amount for the well depth and diameter, circulate through every fixture, hold time, then flush the chlorine out away from the septic system and any waterway. And retest afterward through a lab, not by smell.

How long does shock chlorination last?

Until whatever let bacteria in lets them in again. After a one-time event with a fixed cause, one shock can genuinely close the case. When the cause is structural, a buried wellhead, shallow casing, karst pathways, positives commonly return within weeks, which is the retest-fail cycle that eventually brings owners to continuous disinfection.

Does a UV system need electricity and maintenance?

Yes on both, modestly. The lamp draws roughly what a light bulb does and runs continuously, the lamp itself is an annual replacement, and the quartz sleeve wants occasional cleaning. Prefiltration cartridges go on their own schedule. The trade is a predictable small maintenance calendar in exchange for disinfection that does not depend on remembering to re-dose anything.

Does UV change the taste of the water or add anything to it?

No. Light passes through the water and the water passes on; nothing is added, removed, or altered in taste, which is one reason UV became the residential standard over continuous chlorination. If a taste changes after installation, look at the prefiltration cartridges or the rest of the report, not the lamp.

What about continuous chlorination instead of UV?

Chlorinator feed systems still have a place, mainly where the water also needs oxidation for heavy iron or where iron bacteria call for a disinfectant with residence time in a contact tank. They add chemical handling and maintenance that most households do not want for bacteria alone. For a straightforward coliform condition, UV is the simpler machine; for complicated chemistry, the whole-house design conversation decides.

Who installs a UV system if I request a match?

An independent licensed local contractor. Keystone Well Water is a free matching service; we are paid a referral fee by the professional you are matched with, never by you.

UV system vs shock chlorination for a Pennsylvania well

The short answer: shock chlorination is a one-time knockdown and UV is continuous protection, so the right choice depends on whether your bacteria problem is an event or a condition. One clean failure after a known cause, a repair, a flood, a new pump, is the shock case. A well that keeps failing coliform retests has a structural pathway, and in a state with no well construction standards and coliform in 33 percent of wells (Penn State Extension), conditions are common. This guide is the decision, honestly argued in both directions.

What each one actually does

	Shock chlorination	UV disinfection
What it is	A strong chlorine dose circulated through the well and plumbing, held, then flushed	A point-of-entry lamp that inactivates microbes continuously as water flows past
What it treats	The bacteria present that day, in the well and pipes	Whatever arrives, every day, at rated flow
What it cannot do	Stay in the water or close the entry pathway	Fix the wellhead, or work through cloudy, iron-heavy, or scale-forming water without prefiltration
Cost shape	Cheap materials or a modest service call, repeated as needed	Installed system, roughly $600 to $2,500 by national aggregates, plus an annual lamp
The right case	One-time contamination with a known, fixed cause	Recurring positives, karst or shallow wells, or any household done gambling on retests

UV installed range per HomeGuide (2026) and HomeAdvisor (2025); the full cost context is in the treatment cost guide.

The honest case for shocking first

If the story is one event with a cause you can name and fix, shock chlorination plus the repair plus a confirming retest is the complete, cheap answer, and installing a UV system for it would be overtreatment. Shocking is also standard practice after any well work regardless of what else you own. The procedure is publishable DIY, per Penn State Extension, with the cautions in the FAQ below.

The honest case for UV

If the retest keeps failing, the problem is a pathway, not a population, and re-dosing chlorine every few months is paying rent on a problem you could close out. Continuous disinfection sized to your peak flow, NSF/ANSI 55 equipment, with prefiltration as your water requires, converts a recurring gamble into a maintained system, and pairs with the wellhead inspection that addresses the pathway itself. The full engineering story, sizing, prefiltration, what fouls a sleeve, is on the bacteria and UV disinfection page, and where iron or hardness share the report, the staging logic is on the whole-house treatment page.

The one-afternoon decision method

Pull your test history. One failure ever, or a pattern? Two or more coliform positives inside a couple of years reads as a condition, not an event.
Walk the wellhead. Cap sealed and above grade? Ground sloping away? Casing visible and intact? Any well pit? A defect you can see is a cause you can fix, and it moves the decision toward shock-plus-repair.
Name the event, if there was one. Flood, new pump, plumbing work, a period of disuse: a nameable event with a clean wellhead argues for one shock and a confirming retest.
No event, no visible defect, repeat positives: that is the structural case. Price UV, and have the installer inspect the wellhead anyway; the lamp treats the symptom while the inspection hunts the pathway.

What neither one fixes

Disinfection is not treatment for anything except microbes. Neither chlorine shock nor UV touches nitrate, iron, hardness, arsenic, lead, or PFAS, and a bacteria pathway is often a nitrate pathway too, since both arrive with surface water. If your failed coliform test came with other flagged bands, read them together before buying anything; the nitrate page covers the usual travel companion, and a multi-flag report is the whole-house conversation linked above. After either fix, the finish line is the same: a confirming retest through a DEP-accredited lab, then the annual cadence Penn State Extension recommends.

The corridor reality

In the karst counties this site anchors, Lancaster and York above all, surface water reaches wells in days, and the shock-pass-fail-again cycle is a local folk tradition. That is why the decision above so often lands on UV here: not because the technology is fancier, but because the geology keeps reopening the door chlorine closes. Whichever way your case reads, retest through an accredited lab after either fix; the well test guide covers the bands, and the match form is here when the answer is equipment. One last framing worth keeping: the money you spend on this decision is buying certainty about your drinking water, and the cheapest certainty on the menu is always the confirming retest. Whichever column of the table you land in, schedule it before the equipment invoice is filed away.