If you’ve noticed your pool water level dropping faster than usual, you’re not alone. Many pool owners experience water loss, especially during hot weather. However, while some water loss is normal, excessive or ongoing drops in water level can signal a problem that needs attention.
Understanding why your pool is losing water is the first step to fixing it before it turns into a costly repair.
How Much Water Loss Is Normal?
In warm or windy conditions, evaporation alone can cause a pool to lose between 3 and 5 millimetres of water per day. This is more noticeable during heatwaves or when the pool is heavily used.
Water loss may still be considered normal if:
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It occurs during very hot or windy weather
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It slows or stops during cooler days
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There are no visible wet areas around the pool
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Equipment appears dry and functional
If the water level continues to drop regardless of weather or use, it’s time to investigate further.
Evaporation vs Leaks
The two most common reasons for water loss are evaporation and leaks.
Evaporation happens naturally when heat and wind pull moisture from the surface of the water. Leaks, on the other hand, cause water to escape from the pool structure or plumbing system.
A simple way to tell the difference is the bucket test.
How to Do the Bucket Test
- Fill a bucket with pool water and place it on a pool step so the water inside matches the pool level
- Mark the water level inside the bucket and on the pool wall
- Leave it for 24 hours
- Compare the two levels
If the pool level drops more than the bucket level, evaporation is not the only cause, and a leak is likely.
Common Causes of Pool Water Loss
Leaks in Plumbing or Equipment
Small leaks can occur in areas such as pump seals, filter connections, valves, and chlorinators.
Even a slow drip can result in significant water loss over time. You may notice damp patches near equipment or constantly needing to top up the pool.
Cracks in the Pool Shell
Concrete and fibreglass pools can develop small cracks due to general ground movement or nearby construction, age, and structural stress over time.
These cracks allow water to seep out gradually and are often hard to detect without professional inspection.
Faulty Pool Lights or Skimmer Boxes
Water can escape through elements in your pool, such as the light fittings, skimmer boxes, or even return fittings.
These areas are sealed but can degrade over time, especially with heat and chemical exposure.
Backwashing Too Often
Frequent backwashing can remove large volumes of water from the pool. While backwashing is necessary for sand and DE filters, doing it too often can appear like a leak when it’s actually maintenance-related water loss.
Splash-Out and Heavy Use
Large groups of swimmers, pool games, and cannonballs all contribute to water leaving the pool. This is common during holidays and heatwaves, but should stabilise once usage returns to normal.
Why Pool Water Loss Matters
Losing water isn’t just inconvenient. It can cause bigger issues that impact water bills, increased chemical use requirements, equipment running dry with the danger of damaging pumps and skimmers, and structural stress on the pool overall.
If water drops below the skimmer level, the pump can suck in air, leading to overheating or permanent damage.
What to Do If You Suspect a Leak
If your pool is losing water faster than evaporation alone can explain:
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Perform a bucket test
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Inspect around the equipment for moisture
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Check visible cracks or fittings
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Monitor water levels over several days
Avoid running the pump if the water level falls too low, as this can damage the system.
How Regular Maintenance Helps Prevent Water Loss
Routine servicing helps detect early seal failures, hairline cracks, loose fittings, and equipment wear. Addressing these early prevents small leaks from becoming major problems. Professional inspections also ensure:
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Correct pump operation
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Proper filter pressure
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Secure plumbing connections
This not only protects your pool but also helps control water and energy costs.
When to Call a Pool Professional
You should arrange a professional inspection if:
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The bucket test indicates a leak
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You see unexplained wet areas
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Water loss continues despite cooler weather
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Your equipment area shows signs of moisture
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You are unsure where the loss is coming from
Leak detection and equipment checks can save thousands in long-term damage and wasted water.
Some pool water loss is normal, especially in Australian summers. But if your pool is losing more water than expected, it could be a sign of a leak, equipment fault, or structural issue.
Identifying the cause early protects your pool, your equipment, and your water bill.
If your pool water level keeps dropping and you’re unsure why, having it professionally inspected is the safest and most cost-effective next step.
Need help diagnosing water loss in your pool?
A professional inspection can quickly determine whether evaporation or a leak is to blame and help restore your pool to proper working condition.