How Do I Fix Cloudy Water After Heavy Rainfall?

Shock the pool and run the filter continuously. Use a water clarifier if cloudiness persists.

Why Rain Makes Your Pool Water Cloudy

Heavy rain doesn’t just fill your pool. It brings in organic debris, dilutes your chemicals, and changes your water chemistry. Once this happens, your chlorine can’t sanitize properly and particles stay suspended, making the water look murky or dull.

What Rain Introduces to Your Pool:

• Dirt and pollen from the air

• Leaves, twigs, and other debris

• Contaminants from deck runoff

• Algae spores and bacteria

• Dilution of chlorine, pH, and stabilizers

Even clean-looking rainwater contains enough contamination to throw your pool out of balance. That is especially true in regions where acid rain, air pollution, or dust storms are common. Runoff from surrounding surfaces like pavers or grass can add even more problems, including phosphates and nitrogen compounds.

First Steps to Take Right After the Rain Stops

Address the issue quickly to stop it from getting worse. The faster you act, the easier it is to recover clear water.

Step 1: Remove Surface Debris

• Skim all floating leaves, bugs, and debris

• Use a leaf rake to scoop heavier particles from the bottom

• Clean out skimmer and pump baskets completely

Step 2: Turn On the Pool Pump

• Run the pump continuously for 24 to 48 hours

• Set your timer or switch to manual mode

• Check for strong water movement from return jets

Step 3: Backwash or Clean the Filter

Filters work overtime after a storm.

• Backwash DE or sand filters when pressure rises 8 to 10 psi

• Hose off cartridge filters and soak if heavily soiled

Don’t skip this step. A dirty filter can’t catch fine particles that cloud your water.

How to Test Pool Water After a Storm

Once circulation is reestablished, test your water to see what needs fixing. Storms often throw multiple chemical levels off at once.

Use a Test Kit That Measures:

• Free chlorine

• Total chlorine

• pH

• Total alkalinity

• Cyanuric acid (CYA)

• Calcium hardness

• Phosphates (if recurring algae or cloudiness)

Avoid test strips for post-storm recovery. Liquid drop kits or digital readers are more accurate and give a clearer picture of what’s wrong.

Common Post-Storm Imbalances:

1. Low chlorine due to dilution and organic demand

2. Low pH from acidic rain

3. Low alkalinity, making pH bounce easily

4. Diluted CYA, reducing chlorine stability

Steps to Clear Up Cloudy Pool Water

Step 1: Shock the Pool

Add a high dose of chlorine to destroy organic contaminants.

• Use liquid chlorine or cal-hypo granules

• Add at dusk or evening for maximum effect

• Brush the pool immediately after adding

If your chlorine level is already 0, double-shock the pool with 2 lbs of shock per 10,000 gallons.

Step 2: Balance pH and Alkalinity

• Raise pH with soda ash if below 7.2

• Raise alkalinity with baking soda if under 80 ppm

• Allow chemicals to circulate for 6 hours, then retest

Step 3: Add a Water Clarifier

Clarifiers bind small particles so your filter can trap them.

• Follow the product’s dosage chart

• Avoid overusing, which can cause water to get cloudier

Step 4: Vacuum and Brush Thoroughly

• Brush walls, floor, and steps to dislodge debris

• Use a manual vacuum to remove settled particles

• Focus on corners and dead zones where circulation is weaker

Step 5: Run the Filter System Nonstop

Keep your system running for 1 to 2 days after treatment.

• Check filter pressure daily

• Backwash again if pressure rises

If the pool is still cloudy after 48 hours, consider a second round of shock and clarifier.

Advanced Options for Persistent Cloudiness

Use a Flocculant

If the pool remains murky after 2 days:

1. Add a flocculant according to label directions

2. Let the pump run for 1 hour to distribute

3. Shut off the pump and allow particles to settle overnight

4. Vacuum to waste slowly the next day

Floc clears water faster but requires manual cleanup and may waste some water.

Consider Enzyme Cleaners

Enzymes break down oils, lotions, and other organics that chlorine can’t easily destroy. Adding enzymes after a storm helps reduce strain on your sanitizer and filter.

Preventing Cloudy Water After Future Storms

1. Keep Your Pool Covered

A cover keeps out debris and reduces dilution. If heavy rain is predicted:

• Use a solid or mesh cover before the storm

• Drain any collected rainwater from the cover as soon as possible

2. Add Extra Chlorine Before Storms

If you know a storm is coming:

• Lightly shock the pool 12 hours before the rain

• Balance pH and alkalinity to strengthen your pool’s resilience

3. Clean Your Deck Area

Prevent runoff contamination by:

• Sweeping away grass clippings, dirt, and leaves

• Trimming plants and overhanging branches

4. Maintain Strong Circulation

• Keep return jets angled to create circular motion

• Brush low-circulation zones weekly

Good circulation helps stop cloudiness from building up in quiet corners.

Tools That Make Recovery Easier

• Automatic pool cleaner: Helps maintain debris-free water

• Leaf rake net: Picks up heavier debris faster than standard skimmer

• Water level sensor: Tracks changes during rain events

• Phosphate remover: Use monthly if storms are common

Rain Is Inevitable. Cloudy Water Doesn't Have to Be.

With the right steps and regular maintenance, clearing cloudy water after a storm becomes a routine part of pool care. Test early, act fast, and stay on top of circulation and filtration to keep your water clear and swim-ready no matter what the weather throws your way.