Arsenic in your well water isn’t something you can see, smell, or taste. That’s exactly what makes it dangerous. It sits quietly in your water for years while it works away at your family’s health, and the only way to know it’s there is a proper lab test.
If you’re on a private well in Montgomery County or Lehigh County, this matters more than it might in other parts of the state. Both counties sit on or near the Newark Basin, a stretch of ancient sedimentary bedrock that runs through southeastern Pennsylvania and is one of the better documented arsenic hot spots in the region. That doesn’t mean your well has a problem. It means testing isn’t optional, it’s just smart.
This guide walks through where arsenic comes from in Montgomery and Lehigh County well water, what your test results actually mean, and what treatment looks like once you know what you’re dealing with.
In This Guide
- Understanding Arsenic in Montgomery and Lehigh County Well Water
- Health Risks of Arsenic Contamination
- Pennsylvania Arsenic Regulations and Standards
- Testing Your Well Water for Arsenic
- When to Test
- Testing Process
- Understanding Your Results
- Arsenic Removal Systems and Treatment Options
- Reverse Osmosis Systems
- Specialized Arsenic Filters
- Whole House vs. Point-of-Use Treatment
- Choosing the Right Treatment for Your Home
- Maintenance and Long-Term Care
- Real Estate Considerations
- Schedule a Free Water Test
- FAQs
- Conclusion
Understanding Arsenic in Montgomery and Lehigh County Well Water
Arsenic gets into groundwater the natural way, by dissolving out of the rock and soil the water passes through on its way into your well. In most of Pennsylvania this isn’t much of a concern. In Montgomery and Lehigh counties, the geology makes it one.
Both counties sit along the Newark Basin, a band of Triassic era sedimentary rock, mostly red shale, mudstone, and sandstone, that stretches from Bucks County southwest through Montgomery, Chester, and Berks counties before curving north into the Lehigh Valley. Research from the U.S. Geological Survey has found that arsenic in this rock tends to concentrate in the darker gray and black shale layers, where it binds to iron minerals and gets released into groundwater under the right chemical conditions.
One of the most studied arsenic sites in the region sits right on the Montgomery and Berks county line near Gilbertsville. After elevated arsenic, boron, and fluoride turned up in groundwater there in the early 2000s, the USGS investigated wells across the Newark Basin and confirmed that the pattern wasn’t limited to one property. It’s tied to the bedrock itself, which means it shows up anywhere that same rock does, including well clusters throughout Pottstown, Royersford, Schwenksville, Collegeville, and Skippack. If you’d like more background on how this connects to other water quality concerns in the area, our article on the unregulated contaminants found in Montgomery County water covers the wider picture, and our piece on the groundwater contamination near the Boyertown landfill looks at a related site just over the county line.
Lehigh County sits at the northeastern edge of the same basin, where it stretches up through the Lehigh Valley around Allentown, Emmaus, Macungie, and Alburtis. Countywide modeling from federal groundwater surveys tends to show a lower average arsenic exceedance rate here than the Montgomery County stretch of the basin closer to Gilbertsville. That’s useful context, but it’s not a guarantee for any individual well. Arsenic occurrence is famously patchy. Two wells a few hundred feet apart, drilled into slightly different rock layers, can come back with very different results. A countywide average tells you the odds, not what’s in your glass.
Montgomery County
Wells around Pottstown, Royersford, Schwenksville, and the Gilbertsville area sit near the documented core of the Newark Basin’s dark shale layers, where arsenic has shown up most consistently in past USGS sampling.
Lehigh County
Wells around Allentown, Emmaus, Macungie, and Alburtis sit near the basin’s northeastern edge. Lower countywide exceedance rates on average, but individual wells still vary depending on which rock layer they’re drilled into.
Unlike bacterial contamination, which can make you sick within days, arsenic exposure builds slowly. You could drink from a contaminated well for years with no symptoms at all. Your well’s age doesn’t tell you much either. A brand new well drilled into the wrong layer of shale can test high on day one, and an older well that tested clean a decade ago can develop a problem as water chemistry shifts underground.
Health Risks of Arsenic Contamination
Long term arsenic exposure through drinking water is a serious health concern. The EPA classifies arsenic as a known human carcinogen, with documented links to several types of cancer.
Children face particular risk because their smaller bodies absorb contaminants more readily, and early exposure can affect cognitive development and raise cancer risk later in life. Pregnant women should be especially cautious too, since arsenic exposure can affect fetal development and birth outcomes.
The good news is that these risks are preventable. A properly sized and maintained treatment system removes arsenic effectively, which takes the exposure off the table entirely.
Pennsylvania Arsenic Regulations and Standards
Pennsylvania follows the EPA’s maximum contaminant level (MCL) for arsenic, which is 10 parts per billion (ppb), or 0.010 milligrams per liter. That standard applies to public water systems. If you’re on a private well in Montgomery or Lehigh County, nobody is enforcing it on your behalf. Pennsylvania is one of only two states with no statewide regulation requiring private well construction, maintenance, or water testing of any kind.
The Pennsylvania Department of Environmental Protection (DEP) still recommends that private well owners test for arsenic, particularly in areas with known geological risk factors like the Newark Basin. For real estate transactions, DEP-compliant testing may need to include arsenic depending on the property’s location, and some mortgage lenders now require it for homes on private wells in this part of the state.
Testing Your Well Water for Arsenic in Montgomery and Lehigh Counties
When to Test
Test your well for arsenic if any of the following apply to you:
The Penn State Extension recommends testing private wells annually for bacteria and roughly every three years for chemical contaminants like arsenic. In parts of Montgomery County closer to the basin’s documented core, including the corridor around Pottstown and Gilbertsville, we tend to recommend leaning toward the more frequent end of that range. Our articles on what’s actually in Pottstown’s water and seasonal well testing in Schwenksville go into more detail on timing for those areas specifically. For Lehigh County well owners, our guides on testing your well in Alburtis and what Lehigh Valley homeowners should know about their water walk through the same idea for that part of the region.
Testing Process
Arsenic requires laboratory analysis. You can’t detect it with a home test strip. Proper sample collection matters too, since the results are only as good as the sample.
Flush the system. The tap is run for a few minutes to clear standing water from the pipes before the sample is collected.
Collect from a cold tap. Usually the kitchen faucet, using a specific container provided by a certified lab.
Chain of custody. Professional testing services handle sample handling and documentation, which matters most if you need DEP-compliant results for a real estate transaction.
Our team handles this from start to finish. Fill out the contact form on this page and someone from our water testing team will get in touch to schedule a visit and walk you through what your results mean once they’re back. You can also read more about what our water testing and analysis service covers.
Understanding Your Results
Arsenic results come back in parts per billion (ppb). Here’s how to read them:
| Result | What it means |
|---|---|
| Below 5 ppb | Generally considered low risk |
| 5 to 10 ppb | Moderate concern, worth considering treatment |
| Above 10 ppb | Exceeds EPA standard, treatment recommended |
| Above 50 ppb | High contamination, treatment needed promptly |
Arsenic levels can shift with the seasons and with changes in groundwater conditions, so one test is a snapshot, not a permanent verdict. Regular monitoring gives you a much better picture over time, especially if your well sits inside the Newark Basin footprint.
Arsenic Removal Systems and Treatment Options for Montgomery and Lehigh County Homes
Reverse Osmosis Systems
Reverse osmosis (RO) is highly effective for arsenic removal, typically reducing levels by 95 to 99 percent. The system forces water through a semi-permeable membrane that blocks arsenic along with a range of other contaminants.
Point-of-use RO systems install under the kitchen sink and treat the water used for drinking and cooking. These are the more affordable and lower-maintenance option for most Montgomery and Lehigh County homeowners. Whole-house RO systems treat every drop entering the home, which costs more upfront and takes more ongoing maintenance. You can read more about how our reverse osmosis systems are configured for local water conditions.
Specialized Arsenic Filters
Specialized arsenic filters use adsorption media, often iron-based, designed specifically to bind arsenic as water passes through. These systems work best when they’re sized and tuned for your specific water chemistry. pH, iron content, and other minerals all affect how efficiently the media performs, which is exactly why the Newark Basin’s particular geochemistry matters when a system is being designed for a home in Pottstown versus one in Emmaus.
Whole House vs. Point-of-Use Treatment
Point-of-Use Treatment
Focuses on the water you drink and cook with. This is the more practical and affordable approach for most arsenic cases, since ingestion is the primary exposure concern.
Whole-House Treatment
Treats every fixture in the home, including showers. Worth considering if your levels are very high or you want to eliminate exposure through skin contact as well.
Point-of-use RO systems sit at the lower end of this range, while whole-house arsenic treatment with pre-treatment stages sits at the higher end. Your exact cost depends on your arsenic concentration, water chemistry, and whether pre-treatment is needed to convert arsenic III to the more removable arsenic V form.
We regularly run promotions on water treatment systems for homeowners across Montgomery and Lehigh counties. It’s worth checking current offers before you schedule installation.
See Current Water Treatment Specials
Choosing the Right Treatment for Your Montgomery or Lehigh County Home
Your arsenic treatment system should match your specific contamination level, water chemistry, and household needs. A few factors drive the right choice:
Arsenic concentration. Higher levels may call for more aggressive treatment or multiple stages.
Water chemistry. Iron, pH, and other minerals in Newark Basin groundwater affect how well different treatment methods perform.
Household size. Larger families need higher capacity and flow rates.
Budget. Balancing upfront cost against ongoing maintenance expenses.
A qualified water treatment specialist can evaluate your test results and recommend a system built for your well specifically, not a generic package. Our residential water treatment team handles this evaluation directly, and when someone calls us about arsenic they get a real technician on the line, a straight answer about what their results mean, and no pressure to buy more system than they need.
Not Sure What Your Results Mean?
Fill out the contact form on this page and our team will walk through your water test results and treatment options with you, no obligation.
Maintenance and Long-Term Care
Every arsenic treatment system needs regular maintenance to keep working. A neglected system can actually become a source of contamination if filters or membranes aren’t changed on schedule.
RO systems typically need membrane and filter replacements every 6 to 12 months, more often if your water carries high sediment or iron, which is common in parts of Montgomery County closer to the basin’s core. Specialized arsenic filters need media replacement based on usage and arsenic levels, and some systems include monitoring devices that flag when it’s time.
Annual service visits catch small problems before they become expensive ones. If you’re not sure when your well was last fully checked, our guide on the annual well water check-up is a good place to start, and if you’re noticing pressure changes alongside water quality concerns, our article on signs your well pump may be failing covers what to look for in Lehigh County homes specifically.
Real Estate Considerations in Montgomery and Lehigh Counties
Arsenic can affect property values and the pace of a closing. Many buyers now ask for water testing as part of a home inspection, especially for properties on private wells in areas known for the Newark Basin’s geology.
If you’re selling a home with a well in Pottstown, Royersford, or anywhere along that Montgomery County corridor, proactive testing shows good faith and can prevent last-minute delays at closing. A treatment system already installed can even become a selling point. Our Royersford water quality guide and our piece on seasonal well testing in Emmaus both walk through what buyers and sellers in those markets tend to ask about.
For buyers, arsenic testing should be part of your due diligence. Include water testing provisions in your purchase agreement, and budget for the possibility of a treatment system if results come back elevated. DEP-compliant testing may be required for certain mortgage types or in specific parts of the county, and our DEP compliance testing service handles proper documentation for exactly that situation. Our real estate services cover the full process from initial testing through closing.
Our team serves homeowners, buyers, and sellers across Montgomery and Lehigh counties, from Pottstown and Schwenksville out to Allentown and Alburtis. We provide DEP-compliant water testing for real estate transactions and design arsenic treatment systems tailored to each home’s specific results.
💧 A water test takes one visit and gives you a clear answer. No obligation, no pressure.
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Serving Montgomery and Lehigh Counties
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FAQs
How common is arsenic in Montgomery and Lehigh County well water?
It varies quite a bit by location. Montgomery County wells near the documented core of the Newark Basin, including areas around Gilbertsville and Pottstown, have shown some of the more consistently elevated readings in past USGS sampling. Lehigh County wells, sitting nearer the basin’s northeastern edge, tend to run lower on average countywide, but individual results still depend heavily on which rock layer a specific well is drilled into. The only way to know your own well’s level is a lab test.
Can boiling water remove arsenic?
No. Boiling does not remove arsenic, and it can actually concentrate it as water evaporates. Removing arsenic requires a specialized filtration system, such as reverse osmosis or an arsenic-specific adsorption filter.
How often should I test my well for arsenic?
Penn State Extension recommends testing every three years for chemical contaminants like arsenic, on top of annual bacteria testing. If you’re in a Montgomery County area closer to the Newark Basin’s documented core, or if a neighboring well has tested positive, testing every year or two is a reasonable step up.
What’s the difference between arsenic III and arsenic V?
Arsenic shows up in water in two forms, arsenite (arsenic III) and arsenate (arsenic V). Some treatment systems remove one form more easily than the other, and arsenic III often needs to be converted to arsenic V before a filter can remove it effectively. A professional water analysis identifies which form is present so the right treatment gets specified from the start.
Are there any warning signs that my well has arsenic in it?
No. Arsenic has no taste, odor, or color, which is exactly why relying on your senses doesn’t work here. Laboratory testing is the only reliable way to know.
How much does arsenic treatment cost?
Costs vary based on your arsenic level, water usage, and system type. Point-of-use reverse osmosis systems typically cost less upfront than whole-house treatment. A professional evaluation is the best way to find the most cost-effective approach for your specific well.
Can I install an arsenic removal system myself?
Some point-of-use systems are built for DIY installation, but professional installation ensures proper sizing and setup, which matters a lot for a health-related contaminant like arsenic. Getting it wrong doesn’t just waste money, it can leave you thinking you’re protected when you’re not.
Conclusion
Arsenic in Montgomery and Lehigh County well water is a real, geology-driven concern, not a scare tactic. It’s tied to the same Newark Basin bedrock that runs from Gilbertsville and Pottstown up through the Lehigh Valley, and it affects wells unevenly enough that testing your own water is the only way to know where you stand.
Regular testing, the right treatment system for your specific results, and proper ongoing maintenance are what actually protect your family here. Don’t wait for a real estate deadline or a health concern to prompt the first test. If you’re on a private well anywhere in Montgomery or Lehigh County and haven’t tested for arsenic, fill out the contact form on this page or call us at 484-300-2800 to get started.
