Water loss can come from evaporation, splashing, cleaning, an autofill problem or a leak. A fixed daily evaporation allowance cannot rule out a leak in your pool.
Check visible evidence
Record water levels, weather, recent backwashing and water additions. Look from a safe dry location for wet equipment-pad joints, continuous waste-line flow and an autofill that never stops. Do not approach wet electrical equipment or let a pump run with insufficient water.
EPA evaporation comparison
- Choose a 24-hour period without rain or strong wind; keep the pool closed. EPA’s bucket test calls for pool systems and autofill to be stopped. Do not use this procedure during freezing weather or where stopping circulation is unsafe; ask CAS to arrange the test instead.
- Fill a 2.5–5-gallon bucket to about one inch below its rim. Place it securely on a step or bench with at least two-thirds submerged; bucket water should be slightly above pool water.
- Mark or measure both starting levels separately. After 24 hours, compare the drop inside the bucket with the drop in the pool. Greater pool loss suggests a possible leak; it does not locate it.
- Restore the normal safe water level and operating arrangement, and send measurements and weather notes to CAS. Repeat an invalid test affected by rain, refilling or swimmers.
Locate before excavating
Professional isolation and leak location distinguish shell, fittings and underground lines. Do not pressurize plastic plumbing with compressed air, plug drains yourself, excavate based on a guess or drain the pool to chase the water level. Leak-test pressure must respect every connected component’s rating.
Sources and scope
Documentation checked October 11, 2026. Manufacturer examples apply only to the named equipment; confirm your model and revision. This is homeowner assessment and planning guidance, not a claim that your equipment has been inspected.
- EPA WaterSense: Jump Into Pool Water Efficiency — Printed p. 8: evaporation bucket test
- Weld-On: Solvent welding guide (2024) — Printed pp. 3–6, 14–18: assembly, air-test prohibition and cure schedule
- Pentair: Clean & Clear Plus installation/user guide — Printed pp. 1–3, 6–8: pressure, clearances and servicing
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