Is Your Sydney Pool Leaking? How to Separate Water Loss from Evaporation

Reviewed and updated 8 October 2026.

Having to top up more often is worth investigating, but it does not automatically mean the pool shell has cracked. Evaporation, swimmers, backwashing, overflow and equipment leaks can all reduce the level. The first job is to measure the change under known conditions.

A sheltered Shire courtyard pool and an exposed coastal pool will not necessarily lose water at the same rate. Rather than choosing a universal number of millimetres per day, compare your pool with its recent pattern and a simple evaporation check. Good records can make a leak investigation more focused.

Create a water loss record

Choose a fixed reference point that is easy to photograph and record the water level at the same time each day. Note weather, swimming, cover use, backwashing, water features and any top up. If you have an automatic top up, follow its instructions for a monitored test so it does not conceal the loss.

Keep the water within the equipment’s safe operating range throughout. Do not deliberately allow it to fall until a suspected leak stops. A low level can affect circulation, and leaving a pool substantially empty creates risks that a simple diagnostic check does not justify.

Use a bucket comparison carefully

AstralPool describes a bucket comparison in its pool owner FAQs: mark water levels in a bucket and the pool, then compare their changes. The principle is that the bucket provides a reference for evaporation. A greater fall in the pool suggests that another source of loss needs investigation.

Use a stable, intact bucket in comparable exposure and keep it secure within the pool barrier, away from unsupervised children. Mark each starting level clearly. Avoid swimming, deliberate water replacement and backwashing during the comparison, and record any rain. A tipped bucket or a changed cover arrangement invalidates the comparison. Empty and remove the bucket when finished.

Treat the result as a screening check, not a leak location. Wind, shade and differences in water temperature can affect the comparison. If conditions change substantially, repeat under more consistent conditions instead of drawing a firm conclusion from one uncertain result.

Look for visible losses first

From a safe, dry position, inspect the equipment pad while the system is operating normally. Look for drips or wet tracks near accessible pipe unions, the filter, pump and heater connections. Photograph the location and note whether it is wet only during operation. Keep hands away from live electrical components and moving parts.

Where the waste discharge is safely visible, note any unexpected flow while a media filter is in its normal filtering mode. Report it rather than dismantling a multiport valve. A discharge path can hide significant water loss without creating a puddle beside the pool.

Describe when the loss happens

Tell the technician whether you noticed a change after an equipment repair, heavy rain, a new heating schedule or a period away from home. If you already have comparable observations with the pump running and stopped, include them. Do not alter complex valve arrangements or abandon necessary circulation to create a test without advice.

Greater loss during pump operation can help direct an investigation towards operating equipment or plumbing, but it is not proof of a particular fault. Similar loss at different operating times also does not prove a shell leak. Several pathways can exist at once.

Know when an inspection is urgent

Rapid loss, soil washing away, new movement in paving or water threatening electrical equipment needs prompt attention. Keep people away from unstable ground and stop affected equipment if it is unsafe. Do not dig around the pool or inject a sealing product simply because a crack is visible.

A fine surface mark and a structural leak require different assessments. Photograph changes with a ruler in view where safely possible, but avoid entering the pool or removing fittings to investigate. Specialist testing should establish the likely source before repair work is chosen.

Prepare for leak detection

Gather your water record, bucket comparison, pool construction details, equipment photographs and any plans showing plumbing routes. Tell the provider which parts are accessible and whether the pool has an attached spa, water feature or concealed equipment area.

Ask what the proposed investigation includes, how findings will be documented and whether repair work is quoted separately. Equipment inspection, dye testing and plumbing pressure testing answer different questions. A useful result identifies the evidence for the proposed repair, not just the fact that water is disappearing.

Verify the repair with the same measurement

After a repair, repeat the water level record under comparable conditions. Review any diluted salt or water balance as part of normal maintenance. Sydney Water’s pool water saving advice also highlights evaporation control and avoiding unnecessary backwashing. For visible equipment problems, start with a pool equipment assessment.