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Should You Drain Your Pool in Winter?
As temperatures drop and the swimming season ends, many Aussie pool owners ask:
Should I drain my pool in winter?
The short answer? No — unless absolutely necessary.
Draining your pool can lead to serious structural, chemical, and safety problems if not handled correctly.
In this post, we explain why draining is usually a bad idea, when it might be unavoidable, and how to maintain your pool safely during the colder months.
Why Most Pools Should Stay Full in Winter
Even when you’re not swimming, keeping your pool full helps:
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Maintain structural stability
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Protect the pool surface from sun damage
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Prevent shifting due to groundwater pressure
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Reduce the cost and effort of refilling come summer
What Happens If You Drain Your Pool?
| Risk | What It Causes |
|---|---|
| Surface damage | Fibreglass and vinyl can dry out, shrink or crack |
| Structural failure | Concrete pools can shift or pop out due to hydrostatic pressure |
| UV exposure | Uncovered shells fade, blister or crack |
| Expensive refill | Refilling in summer may be costly or restricted |
| Algae and debris | Empty pools collect dust, pests and become safety hazards |
When Is Draining Actually Necessary?
There are only a few legitimate reasons to fully drain a pool:
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Major repairs or resurfacing
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High cyanuric acid (CYA) or calcium levels that can’t be diluted
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Changing sanitation systems (e.g. chlorine to fresh water or mineral)
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Water contamination from black algae or biohazards
If none of these apply, don’t drain. Instead, winterise the pool correctly.
Partial Draining: A Better Option
If chemical levels are off, partially draining and topping up is safer.
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Lowers CYA, calcium, or TDS (total dissolved solids)
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Reduces water waste
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Avoids exposing your pool surface
You only need to remove 25–50% of the water to correct many issues.
Winter Pool Maintenance Tips
Even when it’s cold, your pool still needs attention.
✅ 1. Balance Your Water
Test for:
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pH (7.2–7.6)
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Alkalinity (80–120 ppm)
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Calcium (200–400 ppm)
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Chlorine (1–3 ppm)
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CYA (30–60 ppm)
Imbalanced water causes corrosion, scale, or algae even in winter.
✅ 2. Reduce Filtration Time
Cut back pump run time to 2–4 hours per day.
Cooler water slows algae growth and chemical breakdown.
✅ 3. Use a Winter Algaecide
Prevents green water without needing daily chlorination.
Add monthly during the off-season.
✅ 4. Keep the Pool Covered
A good cover:
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Blocks UV rays and algae growth
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Stops leaves and debris
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Helps maintain water temperature
Explore pool covers in our pool products section.
✅ 5. Monitor Water Level
Rain and evaporation still occur in winter.
Keep the water level halfway up the skimmer box for proper pump function.
What If You Must Drain Your Pool?
If draining is unavoidable:
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Check with a pool professional first
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Use a hydrostatic valve (for concrete pools)
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Avoid doing it during rainy seasons
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Refill as quickly as possible
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Don’t leave it exposed for long
Unsure if draining is necessary? Chat with our team or visit our pool products page for winter solutions.
Conclusion
So, should you drain your pool in winter?
Almost never. Keeping your pool full helps maintain structure, chemistry, and prevents costly damage.
If levels are off, try a partial drain and refill instead.
Otherwise, balance your water, cover your pool, and reduce pump run time to keep it clean and ready for next season.
Need help with winterising gear or maintenance?
Browse our pool products or visit us in-store for expert advice.
FAQ
No, not unless you’re doing repairs or fixing major water issues. Draining can damage pool surfaces and structure, especially in winter.
Empty pools can crack, shift, or pop out due to pressure from surrounding groundwater. The surface can also dry out and get damaged by UV rays.
Yes. Partial draining helps fix high chemical levels without damaging your pool shell. It’s much safer than full drainage, especially in colder months.
Balance the water, reduce pump time, add algaecide, and cover the pool. These steps protect your pool during the off-season and reduce algae or staining.
No. Run the pump for 2–4 hours daily to keep water circulating and prevent stagnation. This helps maintain chemical balance and avoids algae buildup.
Yes, but at lower levels. Maintain 1–3 ppm of chlorine and add a winter algaecide to reduce chemical demand.
Yes. A cover prevents debris buildup, blocks UV rays, and reduces algae growth. It also helps keep water temperature and chemistry stable.
Only drain after getting professional advice. Use a hydrostatic relief valve, drain slowly, and refill quickly. Avoid leaving the pool empty.
Yes. If you’re planning to go from chlorine to mineral or fresh water, winter is a good time. You may need to partially or fully drain the pool first.
Explore winter algaecides, pool covers, and testing kits in our [pool products](https://www.pumpandpoolpeople.com.au/) or speak with our team in-store.