Filling Your Pool
The average suburban pool with a surface area of 25sqm starts off by containing approx 38,000L of water or, by the time Melbourne Water or the local regulatory authorities apply their charges, (approx $4 / 1000L) $150 of water.
Water Loss due to Evaporation
In terms of evaporative water loss – even with solar heating your pool should only lose water in the peak summer season from mid November through to mid March. On average approx 5 – 10mm of water per day or 0.005 – 0.01m of water will be lost off the surface of the pool. This means a total water loss for the period of 120 days x 25 ( sqm ) x 0.005 – 0.01 = 15 – 30cm of water or 15,000 – 30,000L. Whilst this figure seems high its offset by Melbourne rainfall in this period on average of 250mm for the 120 days or approx 9500L of water hence the average pool will need a net water input of approx 5000 – 20,000L of water for the year or approx $20 – $80 of water.