Cloudy Commercial Pool Water: What Should You Check?

Before you test anything, look for the main drain or reference tile at the deepest point. If you can't see it, the pool closes: the CDC's 2024 Model Aquatic Health Code (MAHC) says a pool bottom that is not visible is an imminent health hazard. Then test chlorine and pH, check that the filter and pump are running, and report it to your operator.

Why does visibility come first?

The MAHC Annex (section 5.7.6) says being able to see the main drain is important for preventing drowning and other injuries.

The 2024 MAHC Code sets these model rules:

• The bottom must be visible, with the water still, at all times the pool is open (section 5.7.6.1).
• Staff use the reference tile at the deepest part of the pool to check clarity (section 5.7.6.1.1).
• The tile or main drain must be visible from any point on the deck up to 30 feet away, in a direct line of sight (section 5.7.6.2).
• Checking water clarity is part of the daily inspection before opening (section 6.4.1.3.1).
• "Pool bottom not visible" is on the list of imminent health hazards, and the owner, operator or supervisor must close the pool for it (sections 6.6.3.1 and 6.6.3.2; check what your state adopted).

With no reference tile, the MAHC Annex suggests placing an object like a submersible manikin at the deepest point.

How do you do the drain check?

1. Let the water go still.
2. Stand on the deck at the farthest point from the deepest drain or tile, up to 30 feet away.
3. Look for the drain or tile in a straight line.
4. Repeat from other sides, and write down the time, where you stood and what you saw.

If you cannot see the drain, clear the pool and follow your closure plan.

What should the first report say?

Include:

• Pool name and the time you saw the cloudy water.
• Whether the drain or tile was visible, and from where.
• The latest chlorine and pH results, with their actual test times.
• Any equipment alarm, and whether swimmers were in.
• Who you told and what they said to do.
• Whether the pool is now open or closed.

Write what you saw, not guesses. "I could not see the deep-end drain from the stand" is a fact. "The filter is broken" is a guess.

Which water tests should you run?

Test free chlorine and pH against the 2024 MAHC limits:

Reading	MAHC model rule	Section
Free chlorine, no CYA	At least 1.0 ppm	5.7.3.1.1.2.1
Free chlorine, with CYA	At least 2.0 ppm	5.7.3.1.1.2.2
pH	7.0 to 7.8	5.7.3.4.1
pH below 6.5 or above 8.0	Imminent health hazard: close	6.6.3.1

The MAHC Annex also links cloudy water to high total alkalinity. High alkalinity pushes pH up, and high pH can cause cloudy water. Share the latest alkalinity result too.

Add new tests at their actual times, without changing earlier entries. For limits at your site, see our guides to the commercial pool chlorine range and commercial pool pH range.

What equipment should you check?

The MAHC (section 6.6.3.1) lists not running the filtration and disinfection equipment all the time as an imminent health hazard. A stopped pump is a closure issue.

Safe steps for most staff:

• Check whether the pump is running and whether any alarm is showing.
• Note gauge readings your training covers, and any open repair request.
• Send this to the operator or service person.

The CDC's pool chemical safety page says to close the pool if the recirculation system is not running, and before servicing the chlorine or pH feed. It says only properly trained people should service these systems. Do not let untrained staff open equipment or change settings.

Who handles treatment and reopening?

Your trained operator chooses any treatment, following the product label. The CDC's guide to operating public pools says to keep filtration and recirculation systems maintained to the maker's instructions and to keep accurate records. For an injury, chemical release or other emergency, follow your emergency plan and call emergency services.

The CDC's chemical safety page says swimmers should not go back in until the feed and recirculation systems have been restarted and run for at least 5 minutes, and water quality meets required standards.

Before reopening, record:

• The drain check result, with time and position.
• Chlorine and pH results after the fix.
• What the operator did, and who approved reopening, when.

Our guide to planning water tests explains the handoff to the next shift.

Poolean keeps water tests, test photos and closures on each pool's record. See the water testing features or book a 30-minute call.

The short version

• Check the drain or reference tile first, from up to 30 feet away on the deck.
• Under the 2024 MAHC, a bottom you cannot see means close the pool.
• Test chlorine and pH, and confirm the pump and filter are running.
• Trained staff handle treatment and equipment.
• Record the checks and who approved reopening.