Does reverse osmosis remove fluoride? How to check a system

What the EPA’s list says

The EPA’s WaterSense page on point-of-use reverse osmosis systems says RO systems can potentially remove water contaminants such as lead, volatile organic compounds (VOCs), PFAS, arsenic, bacteria and viruses. Fluoride is not on that list. The list gives examples rather than a complete inventory, so that does not mean RO cannot reduce fluoride. It means this source does not say so, and you should not take anyone’s general claim, for or against, on trust.

How to check a system for fluoride

The Texas Commission on Environmental Quality’s advice for choosing home water treatment answers the question properly. First, decide what contaminant you want to remove or reduce. Then select a unit certified by NSF, Underwriter’s Laboratory or the Water Quality Association to remove that contaminant, and make sure the certification covers that contaminant, not just the product in general.

For fluoride, that means asking:

1. Is this system certified to reduce fluoride? Which body certified it, and where can I see the listing?
2. Under which standard? NSF/ANSI 58 is the standard for reverse osmosis drinking water treatment systems.
3. What upkeep keeps it working to that certification?

If you want to keep fluoride in your drinking water, ask the same questions the other way round, and ask the pro what the system does to fluoride and how they know.

Is there fluoride in your water to begin with?

Before deciding anything, find out. Whether your water has fluoride added varies from place to place, and it can change. Your own utility’s yearly water quality report tells you about your water. It names where the water comes from and how it is treated, so check the latest one before you decide on any treatment. On a private well, ask a laboratory certified to do drinking water testing whether it tests for fluoride.

Fluoride and health

Whether you should want more or less fluoride in your water is a health question. This site makes no health claims. Ask your doctor or your dentist, and take your water report with you.

If fluoride is the reason you want RO

Tell the pro at the start. It changes which system they suggest and what certification you should ask to see. The same goes if it is the reason you are hesitating. An honest quote answers the question you came with.

• Have your water report or well test to hand.
• Ask for the certification listing for fluoride, in writing.
• Compare any other system on the same point.

Why a general answer is not enough

Some pages answer this question with a flat yes or no and a percentage. Without a source you can check, that tells you little about the system under your own sink. Two systems that both call themselves reverse osmosis can carry different certifications, different stages and different membranes, and upkeep matters as well. That is why the certification for the specific contaminant, fluoride here, is the answer worth having.

Under-sink or whole-house

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. If fluoride is your concern, decide first which water in the house you mean, then ask about the certification of that system. See RO installation and whole-house reverse osmosis.

Keep it working

Whatever a system is certified for, change the filters and membrane on the maker’s schedule, with the maker’s parts. See RO maintenance.

If the pro who can contact you cannot show a certification for fluoride, say so plainly and ask what evidence they do have. You are free to look elsewhere.

For the wider picture, read how reverse osmosis works and does reverse osmosis remove PFAS. When you are ready, send the form and an independent local RO pro can contact you.

Questions people ask