Last checked:
Whole-house vs. point-of-use filters for well water
The right setup depends on what is in your water and how it reaches you. Some problems affect every tap and shower, and some only matter for what you drink. This guide sorts common well problems using what state agencies say, with a source for every claim.
The two types
- Point-of-use (POU) units treat water at one faucet or location: pitchers, countertop units, faucet attachments, refrigerator filters, and under-sink systems. Minnesota's health department calls POU a good option for treating only drinking and cooking water.1
- Point-of-entry (POE), or whole-house, units are installed where the water line enters the home and treat all of the water.1
Minnesota adds that no single unit removes all contaminants, so you may need to combine units.1
Which problems point to which type
| Problem | Usually points to | Why (per the source) |
|---|---|---|
| Iron, manganese | Whole-house | Penn State says they affect all uses of water, so they must be removed with point-of-entry devices.2 |
| Hardness | Whole-house | Maine CDC says softeners prevent mineral deposits and scale buildup.3 |
| Radon | Whole-house | Maine CDC lists aeration or adsorptive media for radon.3 Vermont's Health Department says the major danger from radon in water is breathing it after showers, laundry and dishwashers release it into the air,8 so a single drinking-water tap doesn't address it. |
| Arsenic | Point-of-use is common (whole-house also an option) | EGLE calls point-of-use reverse osmosis or adsorption cartridges the most effective and practical residential treatment, and says whole-house treatment is also an option.4 |
| Nitrate | Point-of-use (RO) or whole-house (anion exchange) | Maine CDC lists reverse osmosis and anion exchange.3 |
| Uranium | Point-of-use (RO) | Maine CDC lists reverse osmosis and notes there's no NSF-certified method to remove uranium.3 |
| PFAS | Either | Maine CDC lists adsorptive media, reverse osmosis or anion exchange.3 |
| Lead, copper | Often point-of-use | Maine CDC lists adsorptive media and RO (and softeners for copper).3 Lead and copper enter drinking water mainly from corrosion of plumbing materials,7 and NHDES recommends testing both stagnant and flushed samples.5 |
| Bacteria | Shock chlorination first | Maine CDC says bacteria is commonly treated with a chlorine bleach procedure.3 Penn State says continuous disinfection is needed if bacteria return after shock chlorination.6 See shock chlorinating a well. |
Trade-offs to know
- Reverse osmosis uses a lot of water. Maine CDC estimates about 2–4 gallons wasted for each treated gallon.3
- Softeners add sodium and can make water more corrosive. If pipes are old, that may cause lead to leach.3
- Adsorptive media needs regular replacement, and anion exchange must be regenerated or flushed regularly.3
- Cost ranges from under $20 to thousands of dollars, depending on whole-house vs. one tap, maintenance, and installation, according to Minnesota.1
Before you buy
- Choose a unit certified by NSF, UL or WQA for the contaminant you're treating, where certification exists.1
- Get several quotes and ask about maintenance and warranty.3
- Be wary of water treatment scams (Minnesota's health department has a page on them).1
- After installation, test the treated water to make sure the system works, then every 3–5 years (NHDES).5
Where to get tested and treatment options
Related guides
- Arsenic in well water
- Iron in well water: what to buy
- Nitrate in well water
- Uranium and radon in well water
-
Minnesota Department of Health, "Home Water Treatment Facts." https://www.health.state.mn.us/communities/environment/water/factsheet/hometreatment.html ↩↩↩↩↩↩
-
Penn State Extension, "Iron and Manganese in Private Water Systems." https://extension.psu.edu/iron-and-manganese-in-private-water-systems ↩
-
Maine CDC, "Quick Guide to Well Water Treatment" (PDF). https://www.maine.gov/dhhs/mecdc/sites/maine.gov.dhhs.mecdc/files/Well-water-treatment8.27.2026.pdf ↩↩↩↩↩↩↩↩↩↩↩
-
Michigan EGLE, "Arsenic in well water." https://www.michigan.gov/egle/about/organization/drinking-water-and-environmental-health/water-well-construction/guidance-materials/arsenic-in-well-water ↩
-
NHDES, "Water Testing Guidance for Private Well Users" (April 2026). https://www.des.nh.gov/sites/g/files/ehbemt341/files/documents/labs-private-wells.pdf ↩↩
-
Penn State Extension, "Shock Chlorination of Wells and Springs." https://extension.psu.edu/shock-chlorination-of-wells-and-springs ↩
-
Livingston County, MI, Environmental Health, "Water Quality Testing for Wells." https://milivcounty.gov/environmental-health/wells/water-quality/ ↩
-
Vermont Department of Health, "Radon in Drinking Water." https://www.healthvermont.gov/environment/drinking-water/radon-drinking-water ↩