7 Things You Should Never Do With Ozone Water Treatment

Updated October 2026 · Gerry Bulfin

Ozone kills bacteria, knocks out sulfur odor and turns dissolved iron into something a filter can catch, with no chemical to buy. It’s also the most misunderstood treatment we sell. Most ozone problems we get called about come from one of these seven mistakes.

Ozone is an oxidizer, not a filter. It changes what’s in the water so the rest of the system can deal with it.

1. Don’t expect ozone to remove iron

Ozone doesn’t remove iron, and neither do chlorine or hydrogen peroxide. All three change dissolved iron into rust particles. A filter then has to catch them, like a Pro-OX iron filter after the contact tank. Skip the filter and you’ve traded clear water that stains for rusty water out of the tap. The same goes for manganese and sulfur.

With manganese, too much ozone can over-oxidize it to permanganate and turn the water pink. Ozone output gets set for your water, not maxed out.

2. Don’t skip the contact tank

Ozone has to stay in contact with the water long enough to finish the reaction. Inject it straight into the line and much of the iron and sulfur passes through unreacted. A contact tank gives it that time and lets the leftover gas separate out. Ozone contact tanks

3. Don’t put ozone into the air

Ozone belongs in water, not in air anyone breathes. The gas that comes off the contact tank is still ozone; OSHA’s limit for workers is 0.1 ppm averaged over 8 hours. An off-gas vent carries it outdoors, never into the house or a closed well house.

4. Don’t use parts that aren’t ozone-rated

Ozone attacks ordinary rubber seals, EPDM gaskets and many metals. Everything it touches before it breaks down needs to be ozone-rated: Viton seals, PVDF (Kynar), PVC or 316 stainless. Ozone breaks back down to oxygen within minutes, so by the time the water leaves the filter there should be none left for your house plumbing.

5. Don’t run the generator on wet air, or without a check valve

Humid air cuts ozone output and can form nitric acid inside the generator. An air dryer fixes that. A check valve keeps water from backing up into the generator, which ruins the ozone cell. Both are cheap compared with the cell. Ozone generators and parts

6. Don’t expect it to soften water

Ozone does nothing to calcium or magnesium. If you have hard water and odor, you need ozone (or another oxidizer) and a softener.

7. Don’t count on it to keep the pipes disinfected

Ozone kills bacteria at the contact tank, then it’s gone. It leaves no residual in the plumbing. If bacteria regrow downstream, as they can with long pipe runs, storage tanks or a well with a history of coliform, chlorine is the better call: it stays in the water and keeps working.

Ozone, peroxide or chlorine?

Hydrogen peroxide systems · Chlorination systems · Ozone systems

New to ozone? Start with Ozone water treatment for well water: 6 things to know first.

Gerry Bulfin is a Grade II California Water Treatment Operator, Master Water Specialist and WQA Certified Installer, and owner of Clean Water Store in Santa Cruz.