Cold Plunge Water Care FAQ: 10 Most Asked Questions

With proper ozone sanitation (30 min × 3×/week) and a working filter, you can go 3-6 months between full water changes. Without ozone, expect to drain every 2-4 weeks. Without ozone AND without a filter, you're draining weekly. Signs it's time: TDS above 1500 ppm, persistent smell, cloudy water that won't clear. See our water care guide.

Regular household bleach (sodium hypochlorite, unscented) can be used as chlorine sanitizer in a pinch — add 1/4 cup per 50 gallons to reach ~2 ppm chlorine. However, pool-grade chlorine (trichlor tablets or sodium dichlor) is more stable, easier to dose, and doesn't contain the additives found in household bleach. For routine use, stick with pool chlorine.

Yes — a quick rinse shower before plunging dramatically extends water life. Body oils, sweat, deodorant, and sunscreen are the primary food source for bacteria in your plunge water. A 30-second rinse removes 90% of these contaminants. If you plunge daily, shower before every session. Your water will last 3x longer.

Most likely chloramines — compounds formed when chlorine reacts with sweat, body oils, or urine. Fix: shock with extra ozone, partial drain and refill, and shower before plunging. If the smell is musty (not chlorine), it's bacterial growth — shock with chlorine, brush the tub walls, run the filter 24 hours. Persistent smell after these steps means it's time to drain and refill.

Keep your plunge at or below 50°F for best water quality. Cold water slows microbial growth significantly — bacteria reproduce 4x slower at 50°F than at 70°F. If you keep your plunge at 55°F or warmer (not recommended for cold therapy anyway), you'll need more aggressive sanitation. The colder the water, the easier water care becomes.

Technically yes, but you'll be draining and refilling every 1-2 weeks. A filter pump catches skin cells, hair, and dust that would otherwise feed bacteria and cloud your water. The Intex C1500 filter pump ($89) pays for itself in saved water bills within 3 months for most residential plunges. Skip the filter only if you drain weekly.

Ozone (O₃) is a gas injected into water that oxidizes bacteria, viruses, and biofilm without leaving chemical residue. It's safe when properly installed inline (water injection). Ozone gas is toxic to breathe, but inline systems dissolve ozone into water where it breaks down to oxygen within 30 minutes. Never use a room-mounted ozone generator near your plunge. See our ozone vs chlorine comparison.

Best option: sanitary sewer cleanout (municipal water treatment handles chlorine and organics). Acceptable: lawn or garden (let chlorine dissipate 24 hours first; don't pour on edible plants). Acceptable: gravel/drainage area (filters naturally through soil; avoid near waterways). NEVER: storm drains (chlorine kills aquatic life; illegal in most jurisdictions).

Likely causes (in order): (1) Low sanitizer — test and add chlorine or run ozone longer. (2) Dirty filter — clean or replace cartridge. (3) High pH — test and adjust to 7.2-7.8. (4) Body oil buildup — shower before plunging. Fix: test water, clean filter, shock with extra ozone, run filter 24 hours. If still cloudy after 24 hours, partial drain and refill.

You can, but there's no advantage for cold plunge use. Bromine is sometimes recommended for hot tubs because it's more stable at high temperatures than chlorine. For cold plunge, bromine offers no advantage over chlorine — and bromine smells worse, costs more, and is harder to find. Stick with chlorine (or ozone + low chlorine).