If you’ve ever looked at a glass of tap water and wondered what’s actually swimming around in it, you’re not alone. Homeowners across Bucks, Chester, Montgomery, Berks, Delaware, and Lehigh counties ask us this all the time, especially those on private wells. Reverse osmosis, or RO, is the system most often recommended for drinking water because it catches what carbon filters and sediment filters simply can’t. Here’s how it actually works, what it removes, what it costs, and how to tell if your home in southeastern PA is a good fit.
On this page:
How an RO system works, stage by stage
What reverse osmosis removes from southeastern PA water
What a reverse osmosis system costs
Do you actually need reverse osmosis?
Reverse osmosis and private wells across our service area
Reverse osmosis vs. other filtration options
What Is Reverse Osmosis?
Reverse osmosis is a filtration process that pushes water through an ultra-fine membrane to strip out dissolved contaminants at the molecular level. Regular carbon and sediment filters can’t do this. They catch particles and improve taste, but they let dissolved solids like lead, nitrates, and PFAS pass right through.
RO systems are almost always installed as point-of-use systems under the kitchen sink, not whole-house systems. That’s on purpose. Treating every drop that enters your home this way is expensive and wastes a lot of water. Treating just the water you drink and cook with gets you the same protection where it counts, and many homeowners also tie it into a refrigerator or ice maker line.
How an RO System Works, Stage by Stage
Most residential RO systems run water through four or five stages before it reaches your glass.
Sediment pre-filter. Water passes through a filter that catches dirt, rust, sand, and other larger particles before they can damage the membrane.
Carbon pre-filter. This stage pulls out chlorine and chloramines, which would otherwise break down the RO membrane over time, and helps with early taste and odor issues.
The RO membrane. This is the core of the system. A quality membrane rejects 90 to 99% of total dissolved solids, including lead, arsenic, nitrates, fluoride, chromium, barium, and radium.
Post-carbon polishing filter. A final carbon pass cleans up any lingering taste or odor right before the water reaches your faucet.
Storage tank. Filtration is slow, so a small pressurized tank holds finished water so you’re not waiting minutes for a glass of water.
Some systems add an optional remineralization stage after the membrane, which puts calcium and magnesium back in. This addresses a common complaint that straight RO water tastes flat or slightly acidic. If taste matters to your household, it’s worth asking your technician about it up front.
What Reverse Osmosis Removes From Southeastern PA Water
A quality RO membrane handles a long list of dissolved contaminants that show up regularly in this region, whether you’re on a well or on municipal water.
RO isn’t a fix for everything, though. It’s worth knowing where its limits are before you assume one system solves every water quality issue.
The only way to know what’s actually in your water, and whether an RO system will address it, is to test first. Guessing at treatment based on symptoms alone is how homeowners end up paying for equipment that doesn’t solve their actual problem.
What a Reverse Osmosis System Costs
Pricing depends on the system’s quality, how many stages it has, and whether your plumbing needs any extra work to accommodate it.
Basic systems start around $200 to $400 for equipment, with mid-range systems that add remineralization or higher capacity running $400 to $800. Professional installation typically adds another $150 to $300, more if you need a new dedicated faucet line or a refrigerator hookup. Filters need periodic replacement too. Expect $50 to $150 a year for pre- and post-filters every 6 to 12 months, plus a membrane swap every 2 to 3 years.
We regularly run promotions on reverse osmosis and other drinking water systems, so it’s worth checking current offers before you schedule an install.
See Current Water Treatment Specials
Do You Actually Need Reverse Osmosis?
Not every home in southeastern PA needs an RO system. Here’s a straightforward way to think about it.
You’re probably a good candidate
Your water tested positive for lead, arsenic, nitrates, or PFAS. You’re on a private well and want the most complete protection for drinking water. You notice a strong chlorine taste, worry about aging pipes, or are tired of buying bottled water.
You may not need RO
Your water tests clean across the major contaminants. You already have whole-house filtration handling your specific issue. Or your main complaint is hardness, which a water softener addresses more directly and efficiently.
The honest answer either way is the same: test your water first. A professional test tells you exactly what you’re dealing with, which tells you exactly what treatment actually makes sense. Buying a system before you test is a bit like taking medicine before you know what’s wrong.
Reverse Osmosis and Private Wells Across Bucks, Chester, Montgomery, Berks, Delaware, and Lehigh Counties
Well water doesn’t get municipal treatment, so whatever’s in the ground around your well can end up in your glass. Southeastern PA’s geology and land use vary a lot from one county to the next, which means the specific contaminants worth watching for vary too.
In parts of Bucks and Montgomery counties, particularly around Horsham, Warminster, and Warrington, PFAS from firefighting foam used at nearby former military bases has been documented in both public and private water supplies for years now. State and local agencies have spent years and millions of dollars addressing it, and it’s a good reminder that PFAS testing is worth doing even outside those specific towns, since the chemicals don’t break down and can travel through groundwater.
In Chester County, arsenic shows up more often in the shale and sandstone bedrock in the northern part of the county, while radionuclides like radium and radon tend to concentrate in areas with quartzite and schist. A long-running USGS groundwater monitoring program in the county has tracked both patterns for decades. Arsenic is odorless and tasteless, so a well owner has no way to know it’s there without testing. The Penn State Extension guide to arsenic in private wells is a solid plain-language resource if you want to read more.
Berks County’s more agricultural stretches, especially around Boyertown, Oley, and Douglassville, see more nitrate concerns tied to farmland runoff, along with a documented PFAS site near the Boyertown landfill. Delaware County’s older boroughs and rowhome neighborhoods carry more lead service lines and lead solder plumbing, which is exactly the scenario where RO earns its keep at the tap even if the water entering the house tests otherwise clean. And in the Lehigh Valley, spring runoff and shallow wells near farmland in towns like Alburtis and Emmaus make seasonal testing especially worthwhile.
An under-sink RO system gives you a strong final layer of protection for drinking and cooking water no matter which of these you’re dealing with. Many well owners in our service area pair it with a whole-house softener or iron filter for the issues that affect plumbing and appliances, and RO specifically for what comes out of the faucet.
Reverse Osmosis vs. Other Filtration Options
Reverse osmosis is one piece of a bigger water treatment picture, not always a standalone fix. Here’s where it fits compared to other common options.
| Method | What It Removes | Best For |
|---|---|---|
| Carbon filter (pitcher or faucet) | Chlorine, taste, odor, some VOCs | Basic taste improvement |
| Water softener | Hardness (calcium, magnesium), some iron | Scale, dry skin, appliance protection |
| Sediment filter | Particles, rust, dirt | Cloudy water, protecting other equipment |
| UV disinfection | Bacteria, viruses | Well water with biological contamination |
| Reverse osmosis | Dissolved solids, heavy metals, nitrates, fluoride, PFAS, and more | Drinking water purity |
Curious how RO stacks up against ultrafiltration specifically? Our ultrafiltration vs. reverse osmosis comparison breaks down when each makes more sense.
What to Look for in an RO System
Want more on choosing between specific setups? We’ve also written a full guide to choosing the right reverse osmosis system for your home, and if you’ve heard some conflicting claims about RO, our article debunking 7 common myths about reverse osmosis systems sorts fact from fiction.
Not sure what’s actually in your water?
A free water test settles the guesswork before you spend a dollar on treatment.
How Dierolf Can Help
Our reverse osmosis service team works throughout Bucks, Chester, Montgomery, Berks, Delaware, and Lehigh counties, testing water, explaining the results in plain language, and recommending treatment based on what’s actually in your water, not a generic sales pitch. If you reach out, a real technician talks you through your options and what installation will actually involve at your house, with no pressure to buy anything on the spot.
If you’re on a well, our well systems team can also look at the bigger picture, whether that’s pairing RO with a softener, an iron filter, or UV treatment. And if you’re in one of the specific towns we mentioned above, we’ve written more locally focused guides too, including pieces on reverse osmosis in Doylestown, reverse osmosis in Quakertown, understanding PFAS in southeastern PA, and removing nitrates from your water.
💧 Find out what’s actually in your water. No obligation, no pressure.
Schedule a Free Water Treatment Consultation
Fill out the form on this page and a real technician will follow up to talk through your water test results and whether reverse osmosis makes sense for your home.
Serving Bucks, Chester, Montgomery, Berks, Delaware, and Lehigh Counties
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FAQs
Do I need reverse osmosis if I already have a water softener?
Yes, often. A water softener handles hardness minerals like calcium and magnesium, but it doesn’t remove dissolved contaminants like lead, arsenic, nitrates, or PFAS. Many homes in our service area run both: a whole-house softener for the plumbing and appliances, and an under-sink RO system for what you actually drink. Filling out the form on this page is the quickest way to find out which combination fits your water.
Is reverse osmosis water safe to drink long-term?
Yes. RO water is safe to drink and is used in homes long-term without issue. Some people notice a flatter taste since RO strips out beneficial minerals along with contaminants, which is why many systems offer an optional remineralization stage to add calcium and magnesium back in.
How long does it take to install a reverse osmosis system?
A standard under-sink installation usually takes a few hours in a single visit, assuming no major plumbing modifications are needed. Adding a refrigerator or ice maker connection can add a bit more time.
Does reverse osmosis waste a lot of water?
Traditional RO systems produce 2 to 4 gallons of wastewater for every gallon of purified water, though newer high-efficiency systems have improved that ratio significantly. If water waste is a concern for your household, ask about high-efficiency options when you fill out the form on this page.
How do I know if my well water needs reverse osmosis?
The only reliable way to know is to test your water. Well owners in Bucks, Chester, Montgomery, Berks, Delaware, and Lehigh counties should test at least annually for bacteria, nitrates, and anything of local concern, such as arsenic or PFAS. If your results show dissolved contaminants, RO is typically the most effective single treatment for drinking water.
Can reverse osmosis remove PFAS from my water?
Yes. Reverse osmosis is one of the most effective residential treatments for PFAS, which is especially relevant for homes in and around parts of Bucks and Montgomery counties with documented PFAS history. A water test will confirm whether PFAS is present in your specific water before you invest in treatment.
