Beat the Heat: Understanding Pool Water Evaporation During Summer
- Sydney Pool Cleaners
- Nov 7
- 3 min read
As Sydney’s summer heats up, pool owners often notice their water levels dropping faster than usual. While it can be tempting to go looking for a leak, the culprit is often simple evaporation - and it can make a big difference to more than just your pool’s water level.
In this article, we outline what warmer weather, evaporation and refilling your pool can mean for water chemistry, equipment functionality and other areas where increased maintenance and awareness is required.
How much water does a pool lose to evaporation?
On average, a backyard pool in Sydney can lose between 3–7 millimetres of water per day during the peak of summer. Over a week, that could mean a loss of around 5cm, easily equating to between 50–100 litres of water lost per square metre of surface area per week.
Of course, individual cases vary and your pool may not fit with these numbers. Several factors influence evaporation rates, including:
Temperature: Hot days and warm nights speed up evaporation.
Wind: Even a gentle breeze can pull moisture away from your pool’s surface.
Sun exposure: Direct sunlight on the water all day increases loss dramatically.
Humidity: Dry air (common during heatwaves) accelerates evaporation.
Why it's critical to maintain your water level
The reason to remain vigilant with your water level (all year round, not just in summer) is the impact it has on your skimmer box, which drives the functionality of your pools equipment and overall health.
Your pool’s water level should always sit about halfway up the skimmer opening.
Too low and the pump can start drawing in air instead of water ... when that happens, your pump can run dry causing overheating, seal damage and potentially mean expensive repairs or total replacement. Too high and your skimmer becomes inefficient, unable to draw in debris and can leave your pool dirty, water chemistry overworked or depleted and create an unsightly, uninviting pool.
Maintaining the correct water level ensures smooth circulation and pump operation, effective filtration, cleaner water and consistent chemical distribution throughout your pool.
If your skimmer box is low on water and struggling to stay full, sucking in air or making unusual gurgling noises, your pool needs topping up - fast.
What happens to your chemistry balance when you top up your pool water
Refilling your pool might seem harmless and simple - you’re just replacing lost water.
Not only can chemicals evaporate along with your water, but every top-up will dilute your pool’s carefully balanced chemistry.
Chlorine: Becomes less concentrated, reducing sanitising power.
pH: Tap water often has a higher pH which can make the pool more alkaline and cloudy.
Total Dissolved Solids (TDS): Over time, minerals and salts can accumulate.
This is why an increase to your servicing schedule will often be recommended throughout warmer months of the year - often double your winter frequency.
How to reduce pool water evaporation
While evaporation can’t be stopped completely, there are ways you can minimise it:
Use a pool cover: A high-quality solar or thermal blanket can reduce evaporation dramatically.
Top up early or late: Refill your pool in the morning or evening when temperatures are lower.
Plant windbreaks: Strategic landscaping (like hedges or fences) can reduce wind exposure - often overlooked as a cause of dramatic water loss.
Maintain correct water levels: Keeping your pool at the right level prevents unnecessary surface agitation.
Recurring maintenance helps prevent costly problems, allows you to accurately budget the pool, takes all the stress out of ownership and keeps your pool sparkling, safe, and swim-ready all year round.
If you’ve noticed your water levels dropping quickly or you’re unsure about your pool chemistry, book a service with Sydney Pool Cleaners today. We’ll help you balance, protect, and preserve your pool water — so all you have to do is dive in.
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