What's Actually in Your Tap Water?

City water vs. well water

The question I ask every homeowner who calls us is the same one: city water or well? That single answer changes almost everything about what we're likely dealing with.

If your water comes from a municipal supply, it's disinfected before it reaches you — usually with chlorine or chloramine. That keeps bacteria out of the pipes, which is a genuinely good thing. But it's also why city water can smell like a pool and taste flat. Older homes add a second layer: lead or copper leaching from aging pipes, solder, and fixtures. And increasingly, city water customers are asking about PFAS — the "forever chemicals" that work their way into municipal supplies from industrial and firefighting sources.

Well water skips municipal treatment entirely. No chlorine taste, but also no safety net — you're responsible for whatever is naturally in your groundwater. The most common complaints I hear from well owners: iron staining on fixtures, a rotten-egg smell from hydrogen sulfide, sediment clouding the water, hardness, and sometimes arsenic from bedrock. Bacteria is the wild card that makes annual testing non-negotiable.

The contaminants worth knowing about

Here's what the research — and the calls I get — says people actually encounter:

• Chlorine & chloramine — The most common complaint in city water, and the easiest to notice. Chlorine is added to kill pathogens; chloramine (chlorine + ammonia) is used by many systems because it's more stable and persists longer in pipes. Both cause taste and odor issues. Chloramine is harder to remove than plain chlorine — standard carbon filters struggle with it; catalytic carbon performed substantially better in one published column test.^[1]
• Fluoride — Added intentionally in many municipal systems for dental health. Generally safe at regulated levels, but some people prefer to reduce it — particularly for infant formula preparation. Catalytic-carbon multi-stage filtration reduces fluoride; reverse osmosis removes it but at the cost of stripped minerals and wasted water.
• Lead & arsenic — You can't taste or smell either one. Lead enters water through corrosion of old pipes, solder, and fixtures — no pipe is too new to be exempt if the fittings are old. Arsenic occurs naturally in bedrock and is especially common in well water in certain regions. Both are serious health concerns at elevated exposure, particularly for children.^[2]
• PFAS / PFOA / PFOS — "Forever chemicals" is the nickname, and it's accurate: these industrial compounds resist breakdown in the environment and in the body. They've been found in municipal water supplies near industrial sites, military bases, and areas where firefighting foam was used. In 2024 the EPA set enforceable limits for six PFAS; in May 2026 it proposed keeping the PFOA and PFOS limits and rescinding the other four.^[3] Catalytic-carbon systems can reduce specific PFAS compounds when backed by product-specific testing, without the wastewater produced by reverse osmosis.
• VOCs (volatile organic compounds) — Solvents, industrial chemicals, and agricultural runoff can introduce VOCs into both groundwater and municipal supplies. Many VOCs are addressed by catalytic carbon; it's one of the reasons we use it as the foundation of our filtration approach.
• Sediment — Particles of sand, rust, dirt, and pipe debris — more common in well water but not unknown in older city systems. Sediment clouding your water is usually visible; sediment in your pipes shortens appliance life even when you can't see it.
• Iron & sulfur — Primarily a well-water issue. Iron causes orange-brown staining on fixtures, sinks, and laundry. Hydrogen sulfide produces the rotten-egg smell many well owners recognize. Neither is usually a direct health hazard at typical levels, but both are miserable to live with and a sign you need whole-house treatment, not just a drinking filter.

How to find out what's in yours

Step one for city water: pull your Consumer Confidence Report. Your utility is required by the EPA to publish one every year.^[4] It lists detected contaminants and how they compare to legal limits. Honest tip: "within legal limits" doesn't always mean "zero" — the report is useful precisely because it shows you what's actually present, even at low levels.

Step one for well water: test. The CDC recommends testing private wells at least annually for coliform bacteria, nitrates, total dissolved solids, and pH — but if you're in a region with arsenic or PFAS concerns, those should be on the panel too.^[5] Our well test kit covers the full panel of contaminants most commonly found in both city and well water, so you're not guessing about what's there.

When I talk to homeowners, I find most people know something is off — the water tastes strange, or there's staining, or they just read a news story about PFAS — but they don't know exactly which contaminants they're dealing with. The report or a test closes that gap and lets you match the right solution to the actual problem. You don't need to know every part number. You need to know your two or three real issues.

What actually removes them

Here's the honest version of what I tell people when they ask about filtration options.

Reverse osmosis (RO) is thorough — it removes a long list of contaminants, including PFAS and fluoride. But a typical point-of-use unit wastes five gallons or more of water for every gallon it produces,^[6] it strips beneficial minerals along with the bad stuff, and it only treats one tap. For most households, there's a better way.

Catalytic carbon multi-stage filtration is the approach I believe in, which is why it's the foundation of every Sentry H2O system we carry. Catalytic carbon goes beyond standard activated carbon — it breaks down chloramine (not just adsorbs it), reduces PFAS, VOCs, fluoride, lead, and arsenic. No wastewater. No stripped minerals.

For drinking water specifically, I point most households toward the 5-stage Sentry H2O Wellness System — an under-sink unit that installs in about 30 minutes with included fittings and tube cutters, no plumber needed. Here's how the five stages work together:

• ToxyGuard — our catalytic-carbon blend. Targets chlorine, chloramine, ammonia, fluoride, VOCs, lead, and arsenic. (PFAS is measured for the full system — see the lab results.)
• Sediment pre-filtration — catches particles before they reach the finer stages.
• Secondary carbon stage — polishes taste and catches anything the first pass missed.
• AlkaGuard — re-mineralizes the water, adding calcium and magnesium and raising pH to approximately 8–9.5. Real benefits: better taste, beneficial minerals, zero mineral stripping. To be clear about the science: these minerals support hydration and taste, but broad "alkaline detox" health claims are debated and I won't make them.
• Final polish — ensures nothing gets through to your glass.

The result is drinking water with reduced levels of the main contaminants, naturally mineralized, and better tasting — without wasting water or requiring a plumber. Filters are replaced at 3,000 gallons or 1 year, whichever comes first. That's it for maintenance.

If your concern is whole-house — every shower, every tap, every appliance — the picture is a bit different and involves tank-based multi-stage systems plus optional UV for microorganisms. But for the drinking water question, the under-sink Wellness System is where I start most conversations.

Frequently Asked Questions

Is tap water safe to drink?

Most municipal tap water meets EPA safety standards, but safe is not the same as clean-tasting or free of everything. Disinfectants, trace metals, and emerging contaminants like PFAS can all be present within legal limits. A consumer confidence report and independent findings for your area show what you're working with — and the right filtration closes the gap.

What contaminants are most common in city water?

Chlorine and chloramine (added for disinfection), fluoride (added for dental health), lead from older pipes and solder, PFAS from industrial or firefighting sources, and VOCs are the most common concerns. Catalytic carbon multi-stage filtration — like the 5-stage Sentry H2O Wellness System — is designed to reduce these at the drinking tap, depending on your water and the system's tested claims.

What contaminants are common in well water?

Iron (orange-brown staining), hydrogen sulfide (rotten-egg odor), sediment, hardness, arsenic from bedrock, and sometimes bacteria are the most common well-water issues. Well owners should test annually with a certified lab. See our full guide: Well water 101 — iron, sulfur, and what to do.

How do I find out what's in my water?

City water customers can download their utility's annual Consumer Confidence Report (required by the EPA). Well owners should test with a certified laboratory at least once a year. Our well test kit covers the full panel of contaminants most commonly found in city and well water — a good starting point before choosing filtration.

Does catalytic carbon remove PFAS?

Yes, when the system is designed and tested for specific PFAS compounds. Sentry H2O's published independent lab reports show PFAS reduction by the under-sink system Mountain Pure Water carries. Those reports are independent testing, not NSF/WQA certification, and unlike reverse osmosis the system produces zero wastewater.

Educational guidance only — not health or medical advice. Consult a licensed water professional or your physician for health concerns related to drinking water quality.