Whole house well water filter

Best for

Homes with orange or black staining, metallic taste or a rotten-egg smell from every tap, where a lab test shows iron, manganese or hydrogen sulfide within the filter's rated range.

Wrong fit

Anyone whose only symptom is a smell from the hot water alone, whose bacteria test came back positive, or whose levels exceed the filter's limits. Those need an anode change, shock chlorination or chemical injection first.

Tradeoff

It needs a drain for nightly backwash, a power outlet and enough pump capacity, and it uses water every time it cleans itself.

What a whole house well filter actually is

On city water, “whole house filter” usually means a carbon cartridge for chlorine. On a well, it almost always means something bigger: a tall tank of oxidizing media with an automatic control head that backwashes itself. Its job is the three nuisance problems that well owners notice first:

• Iron: orange or rust stains in toilets, tubs and laundry.
• Manganese: black or brown stains and slime around drains.
• Hydrogen sulfide: the rotten-egg smell.

Penn State Extension says iron and manganese need to be removed from all water entering the home, so this is a point-of-entry system, not a faucet filter. It treats every tap, including the shower and washing machine, which is where the stains show up.

How oxidizing filters work

Iron and manganese in well water often start out dissolved. Water comes out of the tap clear, then forms orange-brown or black particles as it sits. Penn State notes this “clear water” form is more common below pH 7.0. If you see particles right away, the metals are already oxidized, which is more common in shallow, oxygen-rich sources.

An oxidizing filter converts the dissolved form into particles and then traps them in a media bed. The common designs:

• Air injection (AIO). The tank keeps a pocket of air at the top. Water passes through it, the oxygen converts iron, manganese and sulfur to solids, and the media bed below catches them. SpringWell describes its system this way, with a scheduled backwash each night that flushes the trapped particles to a drain and refreshes the air pocket.
• Manganese greensand. Media coated with potassium permanganate oxidizes and filters in one step. Penn State recommends it for combined iron and manganese of about 3 to 10 mg/L, but it needs regular regeneration with permanganate, which is toxic to handle.
• Birm. Uses dissolved oxygen in the water and needs no regeneration. Penn State says it needs a pH of at least 6.8 for iron and 7.5 for manganese, and its manganese removal is highly variable.
• Catalytic carbon. Effective for dissolved iron below 1.0 mg/L, but it needs at least 4.0 mg/L of dissolved oxygen in the water.

Above those ranges, the usual answer is a chemical oxidant fed ahead of a filter. See chemical injection systems.

What level needs treatment

Lab results are reported in mg/L, which is the same as parts per million (ppm).

EPA’s secondary standards for iron (0.3 mg/L) and manganese (0.05 mg/L) are not enforceable health limits. They mark where staining and taste start. Manganese is the exception that can matter for health: EPA’s health advisory is 0.3 mg/L, and the advisory document flags particular concern for infants. Read more on manganese in well water.

Matching the filter to your numbers

Penn State gives working ranges for each approach. Use them as a first screen, then check the specific product’s limits.

Product specs vary widely. SpringWell, for example, rates its air-injection well filter for up to 7 ppm iron, 8 ppm hydrogen sulfide and 1 ppm manganese, at pH 6.5 to 10. Penn State’s general guidance on aeration is more conservative for sulfur: it says aeration is not usually used above about 2 mg/L hydrogen sulfide. That difference is a reason to send your lab results to the seller and get the fit confirmed in writing before you buy. SpringWell already requires a water test before it ships a well system. If you want to compare one option against those numbers, here is SpringWell’s well water filter.

Where it goes in the treatment order

Order matters when you have more than one problem. A typical well setup runs like this:

1. Sediment screen or cartridge, if the well makes sand or grit. See sediment filters.
2. pH neutralizer, if your pH is below the iron filter’s range. Raising pH first helps oxidation, and Birm-type media needs pH 6.8 or higher. See pH neutralizers.
3. Iron, manganese and sulfur filter.
4. Water softener, if your water is hard. Penn State warns that oxidized iron and manganese foul softener resin, so the iron filter goes ahead of it. See water softeners for well water.
5. UV disinfection, last, because it needs clear, iron-free water.

A reverse osmosis unit, if you have one, sits under the kitchen sink at the end of the line and treats drinking water only.

Install needs

• Drain. Backwashing sends dirty water to a floor drain, standpipe or other approved outlet. SpringWell includes a 50-foot drain line. Check local rules if the drain goes to a septic system.
• Pump capacity. The filter needs a minimum flow to backwash properly. SpringWell’s installation guide lists backwash rates of 5 GPM for the WS1 and 7 GPM for the WS4. Your well and pump need to keep up with that.
• Power. A standard outlet for the control head.
• Space and headroom. SpringWell’s tanks are 10 or 13 inches wide and 64 inches tall with the head.
• Bypass valve. Lets you keep water flowing during service or shock chlorination.
• Pressure and temperature. SpringWell lists 25 to 80 psi and 36 to 120°F. Protect the tank from freezing.
• No water during regeneration. SpringWell’s guide says a backwash cycle runs about 45 minutes, so schedule it for the middle of the night.

Maintenance

Most of the work is automatic, but not all of it.

• Backwash. Runs on a schedule. Check that the drain line is not kinked and that the cycle actually completes.
• Regeneration chemicals. Greensand systems need potassium permanganate. Air-injection systems do not.
• Media. Media wears faster at high iron and sulfur levels. Manufacturer life claims are best treated as estimates.
• Retesting. The Minnesota Department of Health advises testing treated water after installation to confirm the unit works. Then test raw and treated water each year so you spot a slow decline early.

Who should skip it

• Iron under 0.3 mg/L with no manganese or smell. You may not need anything.
• Smell in the hot water only. Penn State says this is usually the water heater’s magnesium anode reacting with sulfate. An aluminum anode often fixes it for far less money. More on hydrogen sulfide in well water.
• A positive bacteria test. Shock chlorinate and retest first. If bacteria persist, plan UV or chlorination. An iron filter is not a disinfection step.
• Levels above the filter’s limits. Look at chemical injection followed by filtration.
• Tea-colored water. That is often tannins, which need a different media.

For a sulfur-only problem, SulfurWaterFilter.com goes deeper on air injection versus chlorine and peroxide.

When to call a pro or the health department

Call a licensed well contractor or water treatment professional if you have heavy slime or iron bacteria, if the problem started after well work, or if pressure is too weak for backwashing. Call your state health department if manganese is above 0.3 mg/L or anyone in the house is an infant. To turn your lab numbers into a treatment plan, enter them at /test-results/.