No Chlorine. No Bromine. How We Actually Keep Our Cold Plunges Clean

Here's a question almost nobody asks before getting into a cold plunge: what's in the water? At most facilities, the honest answer is "the same chemicals as a public pool." At Löyly, the answer is: nothing but cold, clean, continuously filtered water. This is the thing we're most stubborn about, so let's lay it all out.

No chlorine. No bromine. Ever.

Every plunge at Löyly runs its own three-stage purification system, cycling continuously:

• UV-C sanitation that eliminates bacteria as water passes through.
• Automated ozone injection for purification. Dissolved ozone oxidizes contaminants and then reverts to plain oxygen, leaving no chemical residue in the water or on your skin. (It's unrelated to atmospheric ozone as an air-quality concern.)
• A 50-micron filter that captures skin oils and debris.

Why it matters even more next to a sauna

People sometimes shrug: "the sauna is a separate room, who cares what's in the tub?" But the water travels with you. Chemically treated water leaves the tub on your suit and your skin, and sauna heat vaporizes those compounds, which means everyone in the room breathes them. Separate rooms don't prevent that. Not putting chemicals in the water does.

The water is changed daily

Most facilities stretch a water change as far as they can, then hit the tub with a chemical shock when it starts to turn. We don't have that option, because we don't use the chemicals. So we change the water instead: daily, and more often on high-usage tubs. What you're looking at when you step in is clean water, not treated water.

Your own tub, your own temperature

One more thing we refuse to do: the single communal cold tub. Every Löyly location runs individual plunges at four temperatures: 41°F, 46°F, 51°F, and 56°F, each with its own filtration and sanitation system. You're not sharing water with anyone, you're not waiting on an appointment, and you pick the temperature that fits the day instead of taking whatever the tub happens to be set at.

Come feel the difference clean water makes. Grab a day pass or look at memberships, and if you have questions about the systems, ask the front desk. We love talking about this stuff, possibly too much.

Quick answers

Do Löyly's cold plunges use chlorine?

No. No chlorine and no bromine. Each plunge uses continuous UV-C sanitation, automated ozone injection, and 50-micron filtration.

How often is the cold plunge water changed?

Daily, and more often on high-usage tubs.

Is ozone-purified water safe?

Yes. Dissolved ozone is a widely used water purification method. It oxidizes contaminants and reverts to oxygen, leaving no chemical residual on your skin.

Are the cold plunges shared?

No. They're individual tubs, each with its own filtration system, at 41°F, 46°F, 51°F, and 56°F.