Reverse osmosis well water system: test the well first

Reverse Osmosis Company is an independent referral service, not an installer or plumber. When you send the form, your details go to an independent local water treatment pro who can contact you and prepare a quote.

Why wells are different

The EPA is direct about it: private well owners are responsible for delivering safe drinking water to their households. Private wells are not regulated by the federal government under the Safe Drinking Water Act, nor by most state governments. More than 23 million households rely on private wells, and a USGS study of 2,100 private wells, cited by the EPA, found about one in five had at least one contaminant above a human-health benchmark.

City water arrives with a yearly report. Well water arrives with whatever the ground put in it, and only a test tells you what that is.

Test the well first

The EPA advises testing a private well every year for total coliform bacteria, nitrates, total dissolved solids and pH. It also advises testing right away if there are known problems in the area, if conditions near the well change (flooding, land disturbance, new construction or industry), or if you replace or repair any part of the well. The CDC gives the same yearly advice, and adds testing more often if the water’s taste, color or smell changes.

• Use a laboratory certified to do drinking water testing. The CDC says to use a state-certified laboratory.
• Ask your local health department: the EPA notes it may provide private well testing for free.
• Keep every result. A pro choosing treatment wants to see them, and the trend over years tells its own story.

What RO can do on a well

The EPA says RO systems can potentially remove water contaminants such as lead, volatile organic compounds (VOCs), PFAS, arsenic, bacteria and viruses. If a well test turns up one of those, RO is one of the treatments worth asking about. Whether a given system removes it depends on the system and its certification, so ask which contaminants the system you are quoted is certified to reduce.

Some well problems are about how the water looks and tastes. The EPA’s secondary standards, which it does not enforce, give iron 0.3 mg/L (rusty color, metallic taste, reddish or orange staining), manganese 0.05 mg/L (black to brown color, black staining) and total dissolved solids 500 mg/L as guidelines. A test above those lines is worth showing to a pro. Some of these problems have other treatments, and whether they need treating alongside an RO system is a question for the pro after they see the test.

Under-sink or whole-house on a well

An under-sink system treats the water at one faucet, the water you drink and cook with. A whole-house RO system is a bigger installation that the installer sizes after a water test. On a well, the test decides which makes sense, and sometimes it is neither on its own. See whole-house reverse osmosis and RO installation.

Problems with the well itself

No water, low pressure, a pump that runs and runs, or a pressure tank that clicks on and off are problems with the well, not the water. They need a well contractor or pump installer, not an RO pro. Well drilling and pump work is licensed by the state in many places, and your contractor should hold the license your state requires.

What to send with your request

• Your most recent well test, with the date and the laboratory’s name.
• What you want treated: a result on the test, taste, smell, staining.
• Whether there is treatment equipment on the well already.
• Whether you want treated water at one faucet or the whole house.

After the system goes in

Keep testing the well every year. An RO system does not replace the test, and a change in the well can change what the system has to deal with. Follow the maker’s schedule for filters and the membrane; see RO maintenance.

Questions people ask