Quick answer
Wisconsin public pools are regulated by ATCP 76, enforced by DATCP and local agent health departments. Our reading of the 2023 revision: free chlorine minimums of 1.0 ppm for swimming pools, 2.0 ppm for wading pools and 3.0 ppm for whirlpools (doubled with cyanuric acid), a 10 ppm maximum, pH 7.2–7.8, whirlpool testing four times a day, and records kept two years.
- FC minimums: 1.0 pool · 2.0 wading · 3.0 whirlpool (doubled with CYA).
- pH operating range 7.2–7.8.
- Whirlpools: pH and sanitizer tested 4 times a day.
- Records retained 2 years.
ATCP 76 water chemistry at a glance
| Parameter | Swimming pool | Wading pool | Whirlpool |
|---|---|---|---|
| Free chlorine minimum | 1.0 ppm | 2.0 ppm | 3.0 ppm |
| With cyanuric acid | Doubled | Doubled | Doubled |
| Free chlorine maximum | 10 ppm | 10 ppm | 10 ppm |
| Bromine | 3.0 – 10 ppm | 4.0 – 10 ppm | 4.0 – 10 ppm |
| pH | 7.2 – 7.8 | 7.2 – 7.8 | 7.2 – 7.8 |
| Max temperature | — | — | 104°F |
Wisconsin testing and recordkeeping
- Whirlpools: pH and sanitizer tested four times per day.
- Standard pools: tested at opening and at peak use, with frequency depending on whether electronic monitoring is installed.
- Combined chlorine at or above 0.4 ppm calls for breakpoint chlorination — see our breakpoint guide.
- Turnover (ATCP 76.11 Table A): 6 hours for swimming pools, 1 hour for wading pools, 30 minutes for whirlpools; therapy and exercise pools 0.5–4 hours (Table B). Check yours with the turnover rate calculator.
- Records must be kept for two years and be available to inspectors.
- Indoor pools, therapy pools and whirlpools: under the 2023 revision, cyanuric acid (stabilizer) may no longer be used — the phase-out took effect September 24, 2025.
| Venue | What to test | When | Where to record it |
|---|---|---|---|
| Whirlpool / spa | Sanitizer (FC or bromine) & pH, water temperature | 4 times a day | Spa page — one row per day, four test blocks |
| Swimming pool | Sanitizer & pH | At opening and at peak use (frequency depends on electronic monitoring) | Pool chemistry page — OPEN and PEAK lines |
| Any pool with a controller | Compare ORP / controller reading with a manual test | With each manual test | Note the controller reading next to the manual result |
| All pools | Combined chlorine | Daily | Breakpoint chlorinate at 0.4 ppm or higher and log it |
When to close a Wisconsin pool or whirlpool
- Free chlorine or bromine below the minimum for the pool type (doubled when stabilizer is used).
- pH below 6.8 or at/above 8.0.
- Whirlpool water above 104°F.
- Main drain not clearly visible from the deck.
- A diarrheal fecal incident — follow the CDC contamination response steps.
Writing these limits into your log each day is tedious. The Commercial Pool & Spa Log Book has a blank "your local code" column on its limits page so you can write the ATCP 76 numbers in once.
Using the free log in Wisconsin
The Commercial Pool Log PDF uses CDC MAHC reference values on its cover, with a blank "your local code" column. Wisconsin operators should write the ATCP 76 limits above into that column, use one chemistry page per pool per month, and use the spa page for whirlpools to capture the four daily tests.
Frequently asked questions
What is ATCP 76?
ATCP 76 is Wisconsin’s administrative code for public swimming pools and water attractions, administered by the Department of Agriculture, Trade and Consumer Protection (DATCP) and local agent health departments.
How often do Wisconsin whirlpools need to be tested?
pH and sanitizer are tested four times a day for whirlpools under ATCP 76.
How long must Wisconsin pools keep records?
Two years.
What pH is required in Wisconsin public pools?
An operating range of 7.2 to 7.8. Close the pool if pH falls below 6.8 or reaches 8.0 or higher.
Can Wisconsin indoor pools use stabilizer (CYA)?
Under the 2023 revision of ATCP 76, cyanuric acid is phased out for indoor pools, therapy pools and whirlpools; the phase-out took effect September 24, 2025. Confirm with your agent health department.
This page is an educational summary, not legal advice. Pool and spa codes differ by state and county and change over time — always confirm requirements with the health department that inspects your facility.