Perth pool evaporation calculator
How much water your pool loses between October and March
A solar cover can cut evaporation by up to 97%, which on your pool is up to 45,812 litres kept in over the season. A 250B cover for a pool this size is $462.40; a 10-year 525 is $838.40.
How this is worked out
Every millimetre of water that evaporates from one square metre of pool is one litre. The calculator multiplies your pool's surface area by the average daily evaporation for each month in Perth, from 5.3mm a day in October up to 10.2mm a day in January, and adds up the days. Those monthly averages, and the up-to-97% saving for a fitted cover, come from the Town of East Fremantle's pool cover fact sheet. Wind, shade and how often the pool is used will move your real figure up or down.
Why it matters
Evaporation isn't just water. Each top-up dilutes your chlorine and shifts the water balance, so you spend more on chemicals as well. A cover also holds heat in overnight, which is why a covered pool is usually warmer in the morning. If your pool is heated, look at solar vs thermal covers first. For prices on every grade and pool size, see how much a pool cover costs in Perth.