Your Pennsylvania well test, explained
You are probably here holding a lab report for a Pennsylvania well, from the Penn State Agricultural Analytical Services Lab, a county conservation district drive, or a DEP-accredited lab, and nobody has told you what to do with it. That is normal here: the state sets no water quality standards for private wells, so no agency follows up on a bad result. This guide walks every common band on that report, in the order Pennsylvania wells actually fail: what the number means, when it matters, and which treatment technology class is designed to address it. Where a fix involves equipment, we can connect you with an independent licensed local contractor; the interpretation below is free either way.
First, how to read the report itself
Lab reports compare your water against two kinds of federal reference levels. Health-based standards (maximum contaminant levels, MCLs) mark where a contaminant becomes a health concern; secondary standards mark nuisance levels for staining, taste, and odor. Both legally bind public water systems only. About 40 percent of tested Pennsylvania wells fail at least one health-based standard, per the Center for Rural Pennsylvania survey reported by Penn State Extension, so a flagged line puts you in large company. The sections below take the bands one at a time.
Total coliform and E. coli: the Pennsylvania flagship
Reported as present or absent. Present for total coliform means surface-influenced water is reaching your well; present for E. coli means fecal contamination, and drinking untreated water with E. coli can cause gastrointestinal illness, per Penn State Extension. This is the most commonly failed test in the state: coliform shows up in 33 percent of Pennsylvania wells and E. coli in 14 percent, per Penn State Extension, largely because wells built to no construction standard let surface water in at the casing, cap, or grouting.
- Absent, both lines: no action needed; retest annually.
- Total coliform present, E. coli absent: confirm with a retest, then fix the pathway. Continuous disinfection, most often an ultraviolet (UV) system, addresses the symptom; a contractor should also check the wellhead for the entry point.
- E. coli present: stop drinking untreated water, switch to boiled or bottled, retest, and treat. Shock chlorination is a short-term knockdown, not a fix; positives commonly return within weeks when the entry pathway remains.
The technology class: point-of-entry UV disinfection sized to your flow, with prefiltration so the light reaches the microbes. The full write-up is on the bacteria and UV disinfection page.
Nitrate
The health standard is 10 mg/L as nitrate-nitrogen. Statewide only about 3 percent of sampled wells exceed it, per USGS monitoring (2015 to 2019 compilation, USGS Pennsylvania Water Science Center), but the agricultural southeast runs far higher, which is why Lancaster and York county well owners see this band flagged so often. Infants under six months are the sensitive group; nitrate above the standard interferes with oxygen transport in their blood, per Penn State Extension, and boiling makes it worse by concentrating it.
Under 10 mg/L: watch it on your regular retest cycle, especially near cropland. Over 10 mg/L: treat before drinking, particularly with a baby in the house. The technology classes: reverse osmosis at the kitchen tap or anion exchange for the whole house, covered on the nitrate removal page.
Iron and manganese
Secondary (nuisance) standards: 0.3 mg/L for iron, 0.05 mg/L for manganese, per EPA. Above those you get orange-brown staining on fixtures and laundry, metallic taste, and black flecks or slime from manganese. Excessive iron affects 17 percent of Pennsylvania private supplies, worst in the northern and western counties, per Penn State Extension. These bands are about livability and plumbing, not acute health, and they are the most common reason Pennsylvania well owners buy treatment equipment.
The technology depends on the form: dissolved (clear-water) iron oxidizes and filters through air-injection or greensand media; already-oxidized (red-water) iron needs filtration; iron bacteria need a different attack entirely. Details and the decision logic are on the iron and manganese removal page.
Hardness
Reported in grains per gallon (gpg) or mg/L of calcium carbonate. Rough working bands: under 3.5 gpg reads soft, 3.5 to 7 moderate, 7 to 10 hard, above 10 very hard. Hardness is not a health standard; it is scale in the water heater, film on glassware, and shortened appliance life. Pennsylvania's limestone valleys, the same geology that stores the groundwater, tend to produce hard well water, though no statewide prevalence figure exists, so treat your own number as the only one that matters.
The technology class: a cation-exchange water softener sized to your gpg and household, certified under NSF/ANSI 44. See the water softening page, including when a softener alone is the wrong answer because iron or bacteria are also on the report.
Lead
The reference level is 15 ug/L in a first-draw sample. In a 2006 to 2007 Penn State survey, 12 percent of first-draw samples from Pennsylvania wells exceeded it, per Penn State Extension. Lead exposure is a particular concern for children's development, per the EPA. In wells the usual source is not the aquifer but the plumbing: corrosive (low pH) water dissolving lead from older solder, brass, and fittings, which is why first-draw and flushed samples often differ sharply.
If flagged: retest with both first-draw and flushed samples, check the pH band on the same report, and treat the cause. Corrosion control (acid neutralizing for low pH) addresses the source; reverse osmosis at the drinking tap addresses the exposure. Both routes run through the whole-house treatment page, because lead treatment is almost always part of a larger water chemistry fix.
Radon in water: the band almost nobody orders
There is no enforceable standard; 300 pCi/L is the reference level most labs cite. Pennsylvania numbers are striking: 64 percent of sampled network wells exceeded 300 pCi/L in USGS monitoring (2015 to 2019, USGS Pennsylvania Water Science Center), and a roughly 900-well Penn State study put the share near 78 percent. Radon in water contributes to indoor air radon as it off-gasses from showers and taps, the same exposure pathway Pennsylvania already takes seriously in air. If your home has an air radon problem and a private well, the well belongs on the suspect list.
The technology classes: aeration systems that vent the gas outdoors, or granular activated carbon (GAC) for lower concentrations. The trade-offs are on the radon in water treatment page.
Arsenic
The health standard is 10 ug/L. Arsenic in Pennsylvania wells is geological and regional: the glaciated northern-tier counties (Tioga and Bradford among them, with the Lock Haven Formation running highest) and pockets of the southeastern Piedmont, per USGS groundwater studies. Long-term exposure above the standard is a documented health risk, per EPA. Arsenic has no taste, smell, or color; the lab line is the only way to know.
If flagged: confirm with a retest through an accredited lab, then treat. Technology classes: adsorptive media or reverse osmosis, chosen partly by which arsenic species your water carries, one of the questions the licensed contractor you are matched with should answer, and part of the whole-house treatment conversation when other bands are flagged too.
PFAS
Pennsylvania set drinking water limits of 14 ppt for PFOA and 18 ppt for PFOS in 2023, per the Pennsylvania DEP. Read the fine print: those limits apply to public water systems. Private wells are not covered, tested, or protected by them, so the honest framing for a well owner is that the state's PFAS protections stop at the public meter (current as of July 2026). If you are near a known PFAS site, an airfield, or a firefighting training area, a dedicated PFAS panel from an accredited lab is worth ordering; it is not part of standard test kits.
The technology classes: granular activated carbon or reverse osmosis, each certified against specific PFAS reduction claims. Details on the PFAS treatment page.
One more band worth reading: pH
The secondary range is 6.5 to 8.5. Pennsylvania wells in sandstone and shale country often run below it, and acidic water is quietly expensive: it corrodes plumbing, which is the usual mechanism behind the lead and copper results above, and it undercuts iron filters, whose oxidizing media want near-neutral water to perform as rated. If your report pairs a low pH with metals at the tap, treat the pH reading as the cause and the metals as the symptom. The fix class is an acid-neutralizing filter (calcite or similar media) ahead of everything else, one more reason treatment gets designed as a sequence rather than bought as a gadget. A high pH is rarer and mostly matters as context for scale and taste.
Total dissolved solids (TDS) reads similarly: not a health line on its own, but a cheap flag. A TDS value that jumps between tests says something changed in the well or the aquifer, and that is your cue to retest the health bands even if the calendar does not call for it yet.
No report yet? Where Pennsylvanians get tested
- The Penn State Agricultural Analytical Services Lab: mail-in drinking water kits, available through county extension offices.
- A DEP-accredited private lab: the route to use for anything you may act on, including transactions and retests after treatment.
- The Master Well Owner Network: trained volunteers offering free guidance on sampling and results, plus periodic no-cost county testing events when programs are funded (check current availability; these come and go).
- County conservation districts and health departments: several in the Lancaster, York, and Berks corridor run periodic screening drives; your district office is the place to ask.
The full options list, including what each route costs, lives in the free well water testing guide.
From result to fix
Every band above ends the same way on purpose: confirm the number, then size the right technology to it. That second step is where an independent licensed contractor earns their fee, and where we can help: tell us your county and what the report flagged, and we connect you with a local professional who handles that problem. The service is free, and the corridor pages for Lancaster, York, and Berks counties carry the local context if you want it first.