CESARE’S 2026 REGIONAL WATER QUALITY REPORT
2026 Southwestern PA Water Quality Report: 13 Counties Compared
Penn State’s water lab publishes county-by-county summaries of the drinking-water samples homeowners submit. This report pulls those numbers together for all 13 Southwestern Pennsylvania counties Cesare’s serves — hardness, iron, manganese, bacteria, pH, corrosivity, arsenic, and nitrate — with honest notes on what they do and don’t mean.
What Stands Out in the 2026 Numbers
Across 3,501 samples submitted from 13 Southwestern Pennsylvania counties, the patterns are clear: hardness medians run from 2.5 to 13.8 grains per gallon, manganese failed in up to half of tested samples, and bacteria appeared in every county’s submissions.
13.8 gpg median hardness
Washington County — the median among submitted hardness samples, about 235.4 mg/L. Very hard water on any scale.
50.0% manganese exceedance
Indiana and Somerset — half of tested samples exceeded the manganese standard: 25 of 50 and 20 of 40.
75.5% total coliform
Greene County — 80 of 106 submitted samples tested positive for total coliform bacteria.
85.7% corrosive samples
Cambria County — 30 of 35 samples with a saturation index fell outside the ±0.5 criterion.
38.7% E. coli
Greene County — 41 of 106 submitted samples tested positive for E. coli.
2.5 gpg median hardness
Cambria County — the lowest median among submitted samples in this report. Soft, but often corrosive.
How to Read This Report
Who the samples come from. Homeowners who chose to send water to Penn State’s lab — often because something already looked, smelled, or tasted wrong. That self-selection skews results worse than the average well.
What the standards mean. Hardness has no EPA maximum. Iron and manganese are secondary standards — aesthetic, not health-based. The corrosivity criterion is a ±0.5 saturation-index window, not a maximum contaminant level.
What this can’t tell you. Nothing on this page measures your water. Wells a quarter mile apart can test completely differently — and sample counts change from county to county and test to test.
The Master Table: 13 Counties Compared
Every county side by side, among submitted samples tested: total submissions, median hardness, and the share of tested samples over the iron or manganese standards or positive for total coliform and E. coli.
| County | Samples | Hardness (gpg) | Iron % | Manganese % | Total coliform % | E. coli % |
|---|---|---|---|---|---|---|
| Allegheny County Water Treatment | 343 | 6.9 | 23.5 | 24.8 | 54.9 | 23.4 |
| Armstrong County Water Treatment | 126 | 5.9 | 28.6 | 37.5 | 70.2 | 23.4 |
| Beaver County Water Treatment | 220 | 9.0 | 20.7 | 29.8 | 52.2 | 12.1 |
| Butler County Water Treatment | 529 | 2.7 | 25.7 | 28.0 | 44.7 | 9.0 |
| Cambria County Water Treatment | 110 | 2.5 | 22.0 | 26.2 | 55.2 | 19.0 |
| Fayette County Water Treatment | 150 | 3.2 | 24.0 | 27.3 | 59.6 | 25.5 |
| Greene County Water Treatment | 110 | 10.6 | 27.8 | 26.3 | 75.5 | 38.7 |
| Indiana County Water Treatment | 160 | 4.8 | 35.7 | 50.0 | 55.6 | 15.7 |
| Lawrence County Water Treatment | 96 | 7.7 | 25.0 | 41.2 | 32.6 | 7.6 |
| Mercer County Water Treatment | 299 | 4.6 | 27.8 | 27.4 | 43.4 | 6.8 |
| Somerset County Water Treatment | 107 | 5.3 | 35.1 | 50.0 | 46.7 | 9.5 |
| Washington County Water Treatment | 443 | 13.8 | 13.6 | 15.3 | 67.9 | 28.7 |
| Westmoreland County Water Treatment | 808 | 5.9 | 16.2 | 26.2 | 53.5 | 15.5 |
Source: Penn State Agricultural Analytical Services Laboratory county drinking-water summaries. Percentages are among samples tested for each parameter; denominators vary.
Hardness, County by County
Median hardness among submitted samples runs from 2.5 grains per gallon in Cambria County to 13.8 in Washington County. Most of the region’s medians sit in the 3–9 gpg band — enough to scale water heaters and spot glassware.
Manganese: Half of Tested Samples Failed in Two Counties
Manganese exceeded the 0.05 mg/L secondary standard in a large share of tested samples region-wide. In Indiana and Somerset counties it was exactly half — 25 of 50 and 20 of 40 samples. Black staining and a bitter, metallic taste are the usual first signs.
Share of tested samples above the manganese secondary standard, among submitted samples. Dots are scaled to the 50.0% maximum in this set.
Iron in Submitted Well Samples
Iron exceeded the 0.3 mg/L secondary standard in 13.6% to 35.7% of tested samples, depending on the county. Orange staining on fixtures and laundry usually shows up before you can taste anything.
| County | Samples over the standard | Share of tested samples |
|---|---|---|
| Indiana | 15 of 42 | 35.7% |
| Somerset | 13 of 37 | 35.1% |
| Armstrong | 10 of 35 | 28.6% |
| Greene | 5 of 18 | 27.8% |
| Mercer | 27 of 97 | 27.8% |
Iron and manganese usually travel together in this region’s water, but manganese is the tougher of the two to remove — it, not iron, usually decides the right equipment.
Bacteria: The Numbers That Matter Most
Total coliform turned up in 32.6% to 75.5% of submitted samples by county, and E. coli — the indicator tied to real contamination risk — in 6.8% to 38.7%. Bacteria results are the strongest argument on this page for testing before assuming.
Six counties, both series to the same 0–100% scale, among submitted samples tested — denominators differ by county.
Corrosivity: The Quiet One
Corrosive water doesn’t stain or smell — it dissolves. In the five counties shown, 67% to 86% of samples with a saturation index fell outside the ±0.5 criterion. The damage surfaces later as pinhole leaks, blue-green staining, and metals in a water test.
The criterion is a ±0.5 saturation-index window, not a health limit. In Lawrence County only 2.7% of samples had pH out of range — yet 58.8% fell outside the corrosivity criterion.
Arsenic and Nitrate: Small Numbers, Worth Naming
Arsenic and nitrate appeared in a minority of the samples tested for them, and the counts are small enough to spell out plainly. In Somerset County, 3 of 29 samples tested exceeded the arsenic standard. That’s a reason to test — not a reason to panic.
| Test | County | Over the standard | Share |
|---|---|---|---|
| Arsenic | Somerset | 3 of 29 | 10.3% |
| Arsenic | Mercer | 6 of 98 | 6.1% |
| Arsenic | Indiana | 3 of 59 | 5.1% |
| Arsenic | Westmoreland | 5 of 140 | 3.6% |
| Arsenic | Allegheny | 2 of 59 | 3.4% |
| Nitrate | Lawrence | 3 of 35 | 8.6% |
| Nitrate | Mercer | 7 of 132 | 5.3% |
Small denominators move fast — treat these as a prompt to include arsenic and nitrate in your next water test.
Every County’s Standout Numbers
One line per county — the numbers that stood out among submitted samples, linked to each county’s full local page.
| County | What stood out among submitted samples |
|---|---|
| Allegheny County Water Treatment | 343 submissions — 54.9% total coliform and 23.4% E. coli among tested samples |
| Armstrong County Water Treatment | 70.2% total coliform (87 of 124) and 70.6% corrosivity (24 of 34) |
| Beaver County Water Treatment | 9.0 gpg median hardness; 67.5% of corrosivity samples (54 of 80) outside the criterion |
| Butler County Water Treatment | 529 submissions — 2.7 gpg median hardness, 9.0% E. coli (45 of 501) |
| Cambria County Water Treatment | 2.5 gpg median hardness; 85.7% of corrosivity samples (30 of 35) outside the criterion |
| Fayette County Water Treatment | 59.6% total coliform (84 of 141); 70.8% corrosivity (51 of 72) |
| Greene County Water Treatment | 75.5% total coliform (80 of 106); 38.7% E. coli (41 of 106) |
| Indiana County Water Treatment | 50.0% manganese (25 of 50); 35.7% iron (15 of 42) |
| Lawrence County Water Treatment | pH out of range in 2.7% of samples — yet corrosivity outside the criterion in 58.8% |
| Mercer County Water Treatment | arsenic in 6 of 98 samples tested (6.1%); nitrate in 7 of 132 (5.3%) |
| Somerset County Water Treatment | 50.0% manganese (20 of 40); arsenic in 3 of 29 samples tested (10.3%) |
| Washington County Water Treatment | 13.8 gpg median hardness (about 235.4 mg/L); 67.9% total coliform (284 of 418) |
| Westmoreland County Water Treatment | 808 submissions — the largest sample set in this report; 16.2% iron, 53.5% total coliform |
Wells, City Water, and What to Actually Test
This report is built from private well and spring samples. Municipal customers get treated, regulated water — but hardness passes through most municipal treatment untouched, and household plumbing writes its own chapter. Either way the next step is identical: test the water you actually drink.
If you’re on a well. Bacteria, hardness, iron, manganese, pH, and corrosivity are the local baseline — this report shows why. Add arsenic and nitrate: both are tasteless, odorless, and only a lab test finds them.
If you’re on city water. Your utility handles disinfection and reporting. Hardness and corrosion in your own plumbing are still yours — and they don’t show up on the utility’s report.
How testing works. A certified laboratory analysis is a paid service, and it’s the foundation of every system Cesare’s builds. We help you scope the right panel, read the results, and engineer treatment around your exact chemistry.
The county report is context. Your property’s test is the diagnosis.
Southwestern PA Water Quality FAQs
Where does the data in this Southwestern PA water quality report come from?
Does this report tell me what is in my tap water or private well?
Which Southwestern Pennsylvania county had the hardest water?
Which Southwestern PA counties had the most manganese in submitted samples?
Which county had the highest percentage of iron samples above 0.3 mg/L?
Which Southwestern PA county had the highest submitted-sample coliform rate?
What does a positive total coliform or E. coli result mean?
Which Southwestern PA county had the highest corrosivity result?
Can water be corrosive even if the pH is normal?
Has arsenic been found above the drinking-water standard in Southwestern PA samples?
What should a private well in Southwestern Pennsylvania be tested for?
How do I know what water-treatment system my home or business actually needs?
Ready for Better Water at Home?
Get a professional water analysis and a custom treatment plan—clear answers, no pressure.
What You’ll Get
- In-home water evaluation
- Clear explanation of results
- Custom system recommendations
- Straightforward pricing (after testing)
- Education-first consultation—no pressure