This guide is written by Echo Water, which sells whole house and under-sink water filtration systems. That matters here: Echo's whole house systems are set up around city (municipal) water, and we don't publish a system designed specifically for private wells. So this guide focuses on what to test and how to match treatment to your results, whichever brand you end up buying.
Short answer: there is no single best water filter for well water, because no two wells are the same. Test first, using a state-certified laboratory. EPA and CDC recommend testing a private well at least once a year for total coliform bacteria, nitrates, total dissolved solids (TDS) and pH, and your local health department can tell you what else is common in your area. Then buy treatment that targets what the test actually found, installed in the right order, and retest to confirm it's working.
Why well water is different from city water
City water is tested and treated by a utility, which must send customers an annual water quality report. A private well has none of that. In EPA's words, "The quality and safety of drinking water from private domestic wells are not regulated by the Federal Government under the Safe Drinking Water Act," and "Private well owners are responsible for delivering safe drinking water to their households."
Well water can also change. Flooding, nearby construction, agriculture, septic systems and repairs to the well itself can all affect what comes out of the tap. That's why a test from five years ago, or a ZIP-code lookup of the nearest city's water, isn't enough. (Echo's own free water quality analysis covers municipal supplies, so it can't tell you what's in a private well.)
What to test for, and when
Every year
- Total coliform bacteria
- Nitrates
- Total dissolved solids (TDS)
- pH
Test again when something changes
CDC recommends testing when you learn of well water problems in your area; after flooding, land disturbances or new waste disposal sites nearby; when you replace or repair part of the well system; when the water's taste, color or smell changes; and when someone in the household becomes pregnant or a child joins the household.
Ask about local concerns
Depending on the geology and land use around you, your health department may suggest adding:
- Arsenic, uranium or radon, which can come from natural rock formations
- Iron and manganese, which cause staining and metallic tastes
- Hardness (calcium and magnesium), which causes scale
- Hydrogen sulfide, the source of a rotten-egg smell
- Lead and copper, which can come from household plumbing
- Pesticides in farming areas, fuel-related chemicals near storage tanks, and PFAS near industrial sites, airports or places where firefighting foam was used
Use a state-certified lab for anything you'll base a purchase on. Home test strips are useful for screening, but they're not precise enough to size a treatment system.
Taking a sample the lab can use
- Use the sterile bottles and instructions the lab sends. Bacteria samples usually have to reach the lab within a set time, so check the schedule before you fill them.
- Sample raw well water, before any treatment equipment, to see what you're dealing with. Once treatment is installed, sample after it too, to see what actually reaches your tap.
- Follow the lab's instructions on running the water and removing the faucet aerator before you fill the bottle.
- Keep every report. Comparing results year to year shows whether your water is changing.
How to read the results
EPA's drinking water limits for public systems are a useful reference point for well owners, even though they don't legally apply to private wells:
| Result | Reference level | Treatment commonly used |
|---|---|---|
| Total coliform or E. coli detected | Any detection calls for follow-up | Find and fix the source (well cap, casing, surface drainage), disinfect the well and retest. Talk to your health department before drinking the water. |
| Nitrate | EPA limit: 10 mg/L (as nitrogen) | Point-of-use reverse osmosis, anion exchange or distillation. Don't boil: boiling makes nitrate more concentrated. |
| Arsenic | EPA limit: 0.010 mg/L (10 ppb) | Adsorptive media or point-of-use reverse osmosis. Ask the lab whether the form of arsenic matters for treatment. |
| Iron and manganese | EPA secondary (aesthetic) guidelines: 0.3 mg/L iron, 0.05 mg/L manganese | Oxidizing filters; softeners can handle low levels of dissolved iron. |
| Hardness | USGS: above 120 mg/L as calcium carbonate is hard, above 180 mg/L is very hard | Salt-based softener, or salt-free scale control if you only want to limit scale. |
| pH | EPA secondary guideline: 6.5–8.5 | Low-pH (acidic) water is commonly treated with a neutralizing filter. |
| TDS | EPA secondary guideline: 500 mg/L | Reverse osmosis at the drinking tap. |
Two cautions. First, a result under a reference level isn't the same as a result of zero, and a result over one isn't something to fix with the first filter you find. Second, treatment choice depends on combinations: high iron changes which softener or UV system will work, for example. A water treatment professional should turn your lab report into a written plan.
Why treatment order matters
Well water systems are usually built as a train, and the order affects whether each stage works:
- Sediment filtration to catch sand and grit.
- Iron, manganese and sulfur treatment, if needed.
- Softening or scale control, if needed.
- Carbon or specialty media for specific contaminants.
- UV disinfection, if needed, last in the line, because UV works best on clear, pre-treated water.
- Reverse osmosis at the kitchen tap for nitrate, arsenic or TDS in drinking and cooking water.
Two sizing questions come up with wells that don't with city water. Backwashing filters and softeners need enough flow from your well pump to clean themselves, so know your pump's flow rate and ask the installer to compare it with the equipment's requirements. And UV systems and some filters need power and a drain near the equipment.
Red flags when shopping for a well water filter
- A seller who recommends equipment before seeing a certified lab report.
- A free in-home "test" that ends in a same-day sales pitch.
- One system promised to fix everything, regardless of your results.
- Claims about bacteria with no disinfection certification (NSF/ANSI 55 covers UV systems) and no plan to retest.
- No plan for follow-up testing after installation.
- Health or disease promises. Treatment reduces specific contaminants; it doesn't treat people.
How Echo's products fit if you're on a well
We'd rather be clear than sell you the wrong system. Here's what Echo publishes about water source for each of its filtration products:
| Echo product | What Echo says about water source |
|---|---|
| ECHO Whole Home Water Filter | Echo's free water analysis is for municipal (city) water. Well owners are asked to call to order a comprehensive test. |
| Echo Whole Home RO System | Engineered for city water applications. The product page asks well owners to call to order a comprehensive test. |
| ECHO RO (under-sink) | No well water guidance is published on the product page. |
| Echo Flow | Requires reverse osmosis or whole-house prefiltration. Unfiltered municipal or well water straight into the Flow is not supported. |
So if you're on a well, the right first step with Echo is the same as with anyone else: get tested. You can call Echo at +1 855 737-1121 to order a comprehensive test, or use a state-certified lab (your health department can give you a list). Bring the results to any conversation about equipment. If your home is on city water, Echo's whole house water filters are the place to start.
Frequently asked questions
What is the best water filter for well water?
The one built around your own lab results. A well with hard water and iron needs different equipment from a well with nitrate or arsenic, and a well with bacteria needs its source fixed and a disinfection plan, not just a filter.
How often should I test my well?
At least once a year for total coliform bacteria, nitrates, TDS and pH, according to EPA and CDC, and again whenever something changes, such as flooding, a well repair or a new taste or smell.
Can a whole house filter make well water safe to drink?
Only if it's matched to what your test found, and only for those contaminants. Carbon filters aren't a disinfection method. If your test shows bacteria, work with your health department on the source and on disinfection, then retest.
Does boiling well water help?
Boiling is sometimes advised for bacteria, but it doesn't remove nitrate, arsenic or lead, and it makes nitrate more concentrated. Follow your health department's instructions for your specific result.
Is an under-sink reverse osmosis system enough for a well?
For drinking and cooking water, point-of-use RO is a common way to reduce nitrate, arsenic and TDS at one tap. It doesn't treat water for bathing or laundry, and RO systems generally aren't meant for water that is microbiologically unsafe unless it's disinfected. Read our under-sink reverse osmosis buyer's guide for what to check.
Sources behind this guide
- EPA: Private drinking water wells
- EPA: Protect your home's water
- CDC: Guidelines for testing well water
- EPA: National Primary Drinking Water Regulations
- EPA: Secondary drinking water standards
- USGS: Hardness of water
- Minnesota Department of Health: Nitrate in well water
Written by Echo Water. Last reviewed September 28, 2026. This is general information, not a substitute for a certified water test or advice from your local health department.
