What to Do If My Pool Overflows After Heavy Rain?

Heavy rain can overfill your pool, dilute chemicals, and wash debris into the water. Don’t panic—here’s how to drain safely, rebalance your water, and prevent future flooding.

Step 1: Drain Excess Water

If water is above the skimmer:
- Use a submersible pump (place in the deep end), venturi pump, or backwash your filter to lower the level.
- Never drain completely—keep water at least halfway up the skimmer to avoid structural damage.
Check drainage: Clear pool deck drains to redirect runoff away from the pool.

Step 2: Remove Debris

Skim leaves, dirt, and organic matter from the surface.
Vacuum the floor to clear silt or mud washed in by runoff.
Clean skimmer and pump baskets to restore water flow.

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Step 3: Test & Rebalance Water

Rain dilutes chlorine and alters pH. Test and adjust:

pH: Aim for 7.2–7.6 (rainwater is often acidic, so use pH increaser if needed).
Alkalinity: Restore to 80–120 ppm with some pool buffer.
Chlorine: Shock the pool to 5–10 ppm to kill contaminants (use chlorine shock or non-chlorine oxidiser).
Cyanuric Acid (CYA): Top up stabiliser if levels drop below 30 ppm.

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Step 4: Clean Filters & Equipment

Sand/DE filters: Backwash thoroughly.
Cartridge filters: Remove and hose down pleats.
Check pump and heater for debris blockages (e.g., leaves in impellers).

Step 5: Prevent Future Overflow

Install an overflow relief: Auto-drain systems divert excess water.
Grade your yard: Ensure landscaping slopes away from the pool.
Use a pool cover: Reduce debris and minimise dilution during storms.

When to Call a Pro

Persistent flooding: Could indicate poor drainage or plumbing issues.
Contaminated water: If storm runoff contains chemicals or ash (e.g., post-bushfire).
Structural concerns: Cracks or shifting pavers around the pool.

Final Tip: Act fast after heavy rain to prevent algae blooms and equipment damage. With quick draining and rebalancing, your pool will bounce back in no time.