The amount of water that a backyard swimming pool loses to evaporation in an Australian summer will depend on several factors, including the size of the pool, the temperature, humidity, wind speed, and the pool's location.
On average a pool can lose between 2 to 5cm of water per week due to evaporation. However, during the summer months, evaporation rates can be much higher. In extreme heat and windy conditions, a pool can lose up to 10cm of water or more per week.
A typical residential swimming pool in NSW has dimensions of 8 metres x 4 metres and an average depth of 1.5 metres. With a capacity of 48,000 litres, and every centimetre lost to evaporation is the equivalent of 320 litres of water.
Let’s consider the hottest 4 months (or 18 weeks) of the year. We’ll assume that evaporation losses are 5cm per week for 12 weeks and 8cm per week for the remaining 6 weeks. That’s a total of 34,500 litres or 72% of your total pool volume!
Of course, any rainfall in the summer months will offset evaporation losses and help to top-up your pool, but it won’t be enough.
In Sydney, average 4-monthly rainfall from December to March is 429mm, so your 8m x 4m pool will collect 13,700 litres of water, meaning you’ll still need another 20,800 litres to top-up. At Tamworth in regional NSW with lower 4-monthly summer rainfall of 271mm, you’ll need 25,800 litres to top-up your pool.
There’s one asset that you have with a much larger area than your pool. The roof area of an average Australian family home is 240m2 – nearly 8x larger than the average pool area! With a simple rainwater capture system and a rainwater storage tank, over the same period, you could harvest over 100,000 litres from a Sydney rooftop and 65,000 litres in Tamworth – more than enough to top up your pool and sufficient for many other uses around the house.
At a rate of $2.35 per kilolitre (1KL = 1,000 litres)*, there’s obviously a cost to topping-up your pool but, consider this – there are an estimated 350,000 residential swimming pools in NSW and if each one requires 21,000 litres to top-up, that’s a whopping 7.5 million kilolitres of municipal water – the equivalent of almost 3,000 Olympic sized pools!
With a growing population and finite water resources, the water minimisation efforts of every household ripple outwards to:
reduce the need for new dams or desalination plants
protect remaining environmental flows in rivers
reduce infrastructure operating costs, and,
decrease stormwater runoff, thereby helping to reduce local flooding and scouring of creeks
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Incorporating the most up-to-date engineering, manufacturing, and chemistry, Rapid Plas have been manufacturing superb quality poly rainwater tanks in Tamworth for over 30 years.
Ready to find out more? Talk to our expert team to find out how to configure your rainwater collection system for all your domestic needs. Call our team on 1800 816 299 or email sales@rapidplas.com.au with your enquiry.
* Source: Sydney Water (www.sydneywater.com.au)
