| Climate/Conditions | Weekly Water Loss (Uncovered) | Annual Gallons Lost (15K gal pool) |
|---|---|---|
| Mild (cool, humid, low wind) | 0.5–1 inch | 5,000–10,000 gal |
| Moderate (typical suburban) | 1–1.5 inches | 10,000–16,000 gal |
| Hot/dry/windy (desert SW, etc.) | 1.5–3 inches | 16,000–32,000 gal |
| Heated pool (82°F+) | Add 30–50% to above | Varies |
Evaporation doesn't just lower the water level — it causes a cascade of problems:
A solar cover (also called a bubble cover or solar blanket) is a UV-stabilized polyethylene sheet with air bubbles that floats on the pool surface. It reduces evaporation by 90–95% by creating a physical barrier between the water and air.
Additional benefits of a solar cover:
Solar covers should be deployed whenever the pool is not in use — at night, during work hours, and especially during windy conditions. A reel system makes daily deployment practical.
Liquid solar covers (isopropyl alcohol or hexadecanol-based products) form a thin molecular layer on the pool surface that reduces evaporation by 30–50%. They are invisible, don't affect swimming, and are added weekly. They are far less effective than a physical cover but useful in situations where a cover is impractical (commercial pools, automatic pool cleaners that get tangled, etc.).
Wind dramatically increases evaporation by constantly replacing the humid air layer above the pool with dry ambient air. A fence, hedge, or wall that blocks prevailing wind can reduce evaporation by 20–40%. This is especially valuable for pools in exposed locations or elevated sites.
Evaporation increases with water temperature — a heated pool at 85°F evaporates significantly more than one at 78°F. Every degree of temperature reduction modestly decreases evaporation. If you heat the pool, always pair the heater with a solar cover to capture the heat you're paying to produce.
The bucket test distinguishes evaporation from a leak: place a water-filled bucket on a pool step so the bucket water is at the same level as the pool. Mark both. After 48 hours, if both dropped equally, it's evaporation. If the pool dropped more than the bucket, suspect a leak.
SplashLens logs water level observations so you can track evaporation rates over time and distinguish normal seasonal loss from a potential leak. A sudden increase in water loss is a diagnostic signal — log it and investigate.
Open SplashLens Free →Typically 1–2 inches per week in summer (250–500+ gallons for a 15,000-gallon pool). Hot, dry, and windy conditions can double this. Over a full season, this adds up to 10,000–30,000 gallons.
Yes — a solar cover reduces evaporation by 90–95%. Liquid solar covers reduce it by 30–50%. The physical cover is by far the most effective, and also retains heat and reduces UV chlorine loss.
High water temperature, high air temperature, low humidity, and wind — with wind often being the biggest driver. A heated pool in a windy, arid location can lose 3–4 inches per week uncovered. Windbreaks and covers address the largest contributors.
The bucket test: fill a bucket with pool water on a pool step. Mark both levels. After 48 hours, equal drops = evaporation. Pool dropped more than bucket = likely a leak. Run the test with the pump off for the most accurate comparison.
Dramatically. Wind continuously replaces humid air above the pool with dry ambient air, maximizing evaporation. Pools in windy or exposed locations can lose 2–3x the evaporation of a sheltered pool. Windbreaks are an effective and underused solution.