Tap water and supplyGuide

Water filters: what to buy for city, well and rural water

By The Downspout · Updated Oct 11, 2026 · 5 min read Share

For city water, a certified carbon filter takes out chlorine. A pitcher is the cheapest start and an under-sink unit is the better long-term choice. For a well, test first, then match the filter. For germs from a well, tank, creek or rain, add a sediment filter and UV.

Our take. We support filtering tap water and well water. Science still has unknowns, and unproven harmful is not the same as proven harmless. A filter cuts some of those unknowns. It does not cut all of them, so test your water too. This is our editorial view, not medical advice.

The filter advice works anywhere. The links to water supplier and county details are for Sonoma County. New to your water? Start with what is in Sonoma County water, and find your source there.

Start with what you want out

No filter does everything. Pick the problem first.

• Chlorine taste and smell: activated carbon. NSF/ANSI 42.
• Health-related contaminants such as lead: a carbon filter certified to NSF/ANSI 53 for that contaminant.
• Dissolved things, including fluoride if added: reverse osmosis. NSF/ANSI 58.
• Germs from a well, tank, creek or rain: UV after a sediment filter. NSF/ANSI 55 for UV.
• Grit and cloudy water: a sediment filter.

If you are on city water, your water report says what is in it. If you have a well, a lab test says. Chloramine is a related disinfectant some suppliers use. If your report says chloramine, ask the maker if the filter is rated for it before you buy.

Best picks for city water

You want chlorine taste and byproducts out. Ranked for most households:

1. Under-sink carbon filter. Best long-term choice. Fits under the sink and filters the water at one tap. EWG lists these at $180 to $456 for the unit, with cartridges of $48 to $137 every 6 to 12 months.
2. Pitcher. Cheapest way to start. Units are $23 to $46. Cartridges are $9.50 to $12 every 2 months or 40 gallons. You fill it by hand and wait.
3. Faucet mount. $30 to $48, with cartridges of about $15 every 2 to 4 months. Small and quick to fit. It slows the flow.
4. Whole-house carbon. $284 to $876 for the unit in EWG's list. It treats every tap. Worth it if you also want the shower filtered, or want to protect the whole house.

Our pick for most renters: a pitcher. For most owners: under-sink carbon.

Best picks for a well

Test first. A filter chosen without a test is a guess. Our well test planner shows what to test and how often. Then match the filter to the result, using the chart in our well water section.

1. Sediment filter, then carbon, at the point where water enters the house. Catches grit first so the other filters last longer.
2. UV, if the test shows bacteria or you want a margin. It kills germs, leaves no chemical and uses power. It does not improve taste or clarity.
3. Reverse osmosis at one tap, for drinking and cooking. For dissolved contaminants the test finds. Only one tap needs it.

HomeAdvisor lists whole-house filters at $1,129 to $3,540, UV units at $500 to $1,500, reverse osmosis at $1,000 to $4,800, and filter upkeep at $50 to $300 a year. Installation labor is $300 to $500. These are national figures. Get local quotes. Our rural water guide has a cost planner where you enter your own quotes.

Best picks for creek, spring, tank or rain water

These sources can carry germs, so the order matters.

1. Sediment filter. Particles can shield germs from UV light, so UV works only on clear water.
2. Carbon filter, if you want taste or some chemicals out.
3. UV. Kills bacteria, viruses, Giardia and Cryptosporidium. Replace the lamp at least once a year.

Boiling for 1 minute (3 above 6,500 feet) also kills them and costs nothing. Filters with an absolute pore size of 1 micron or smaller, or an NSF 53 or 58 cyst rating, stop parasites but not viruses. None of these remove chemicals. See our creek water, tank and rain sections.

The types, cost and upkeep

• Pitcher. Carbon. Good for chlorine taste. Fill, wait, pour. Change the cartridge on schedule.
• Faucet mount. Carbon. Switch between filtered and plain water.
• Countertop. EWG lists $125 to $160, with cartridges of $48 to $60 every 6 months. No plumbing work.
• Under sink. Carbon, often with a second stage. Needs a short install. Cartridges every 6 to 12 months.
• Reverse osmosis. Pushes water through a fine membrane and sends the rest to the drain. Removes the most. Needs a tank, a drain line and filter changes.
• Sediment filter. A cartridge that catches grit and rust. We did not find a sourced price range. Ask a dealer.
• UV. A lamp in a steel chamber. Needs power, clear water and a yearly lamp. Test your water before and after installing it, then yearly. Check for coliform monthly for the first six months.
• Water softener. Treats hard water, not chlorine or germs. HomeAdvisor lists $200 to $6,000.

Cost figures are from an EWG price survey of carbon filters and from HomeAdvisor. Prices change. Cartridge schedules are the makers' own.

What about a homemade charcoal filter?

We found no tested standard for one. A certified filter has been tested. A homemade one has not. Charcoal may clear cloudy water, but CDC says clear water can still be unsafe. Use a homemade filter to clear sediment before boiling or a real treatment, not instead of one.

Read the label

• Look for a certification mark from NSF International, or another accredited tester, on the box.
• Check that the claim names your contaminant. "Reduces" and "certified to remove" are not the same.
• Search NSF's list to confirm a product is certified: NSF certified drinking water treatment units.

Keep it working

• Change cartridges on the maker's schedule. An old filter can stop working and look the same.
• Write the date on the housing the day you change it.
• Retest a well after you add a filter.

Where to buy

Your options are a local water treatment dealer or plumber, or online. A local dealer can size a system to your test. Our directory lists local plumbers and well companies. We have not checked their work.

Online, these searches are a start. Check the certification on any product before you buy:

• Pitcher filters certified to NSF 42 and 53
• Under-sink carbon filters
• Reverse osmosis systems for the kitchen
• Whole-house sediment filters
• UV water systems for well water
• Home water test kits

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What we do not know

• Costs are national and from surveys. Local quotes will differ.
• We have not tested any filter ourselves.
• Filters certified for one contaminant may not reduce another. Check each label.

Related: what is in your water, rural water systems, test your well water.

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