Well Water Filter: Which One Fits Your Water

Test before you buy a well water filter

A filter fixes only the problem it was built for. The Minnesota Department of Health says no single treatment unit can remove all contaminants. Source: Home Water Treatment.

Send a sample to a state-certified lab. Ask for bacteria, nitrate, iron, manganese, hardness, pH and turbidity. Add hydrogen sulfide if the water smells. The NC Department of Health and Human Services says to know hardness, pH, iron and turbidity before you install, because they change how other equipment works. Source: NC DHHS.

Our list of certified labs by state shows where to send it. The well water testing guide explains each test. When the report comes back, the test results explainer reads it line by line.

Well water filter by problem

Find the row that matches your water and your lab report.

The limits in the table come from the EPA. Nitrate (10 mg/L) and arsenic (0.010 mg/L) are enforceable limits for public water. Source: National Primary Drinking Water Regulations. Iron (0.3 mg/L), manganese (0.05 mg/L) and pH (6.5 to 8.5) are secondary guidelines for stains, taste and odor. Source: EPA secondary standards. Private wells are not regulated by these rules, so they serve as a yardstick.

Whole-house filter or one tap?

A point-of-entry unit sits where the water line enters the house and treats every tap. A point-of-use unit treats one tap, often the kitchen sink. Source: Minnesota Department of Health.

• Whole-house: sediment, iron, manganese, sulfur and hardness. These show up at every tap, in the laundry and in the water heater.
• One tap: nitrate and arsenic. These matter in the water you drink and cook with.

Pick a unit certified by NSF, UL or the Water Quality Association for the contaminant on your report, when a certification exists. The Minnesota Department of Health gives that advice. It also says these groups do not certify units for every contaminant.

Sediment filter for a well

A sediment filter catches sand, grit and rust flakes. It does not catch dissolved iron. The Minnesota Department of Health says sediment filters can remove small amounts of red-water iron, but iron plugs them quickly. Source: Iron in Well Water.

Put the sediment filter first, so the equipment after it sees clean water. Septic & Well Pro lists a sediment filter at $200 to $800 installed. Cartridges cost $10 to $30 and last 1 to 3 months. New sand after a pump job or a dry spell can point to a well problem rather than a filter problem. The quick answer on whether a well needs a sediment filter covers that case.

The order of the stages

1. Sediment filter.
2. Iron, manganese or sulfur filter. Penn State Extension says oxidized iron clogs softener resin, so it goes before the softener. Source: Water Softening.
3. Water softener, if the water is hard.
4. UV unit, if bacteria keep coming back. The Minnesota Department of Health says UV may need pre-filtration when turbidity is above 1 NTU. Source: MDH fact sheet.
5. Carbon or reverse osmosis at the kitchen tap, last.

After the install, test the treated water. Both the Minnesota Department of Health and NC DHHS say to retest so you know the system works. Every unit needs upkeep: new cartridges, backwash, salt, or a cleaning.

What a well water filter costs

NC DHHS puts costs at about $500 for a single point-of-use system up to $3,000 for a point-of-entry system. The Minnesota Department of Health fact sheet, based on quotes obtained in 2017 and research in 2018, lists these ranges:

• Oxidizing iron filter: $1,500 to $3,000.
• Water softener: $200 to $3,000.
• Whole-house UV unit: $250 to $800.
• Reverse osmosis at one tap: $300 to $1,500.

Prices change by region and installer. NC DHHS advises quotes from at least three water treatment companies, and a contract that states which contaminants the system will lower. The treatment picker lists the options for your results.

What five states say

• Florida. The Florida Department of Health says hydrogen sulfide can occur in wells anywhere in Florida. If the smell comes only from water treated by a softener, it points to sulfur bacteria in the softener. Source: Well Water Facts: Odor and Staining (PDF).
• Texas. The Texas Well Owner Network says to test at least every year for nitrate, total dissolved solids and E. coli or fecal coliform. Source: Water Well Basics (PDF).
• North Carolina. NC DHHS says many wells in the state have too much lead, arsenic, iron or manganese, low pH, or harmful bacteria. Source: Private Well Water Testing FAQs.
• Michigan. EGLE lists coliform bacteria, nitrate, hardness, iron, manganese, arsenic and lead among the standard concerns for private wells. Source: Private Residential Water Well Testing.
• New York. The state health department links stained fixtures to iron, copper, manganese and hardness. It also says samples go to a lab certified by its ELAP program. Source: Individual Water Supply Wells, Fact Sheet #3.