Living in sunny South Africa, we all try to take in the wonderful African climate we are lucky to have almost daily. The climatic conditions of the country’s region that make having a backyard swimming pool so attractive are those that also create high water evaporation. These conditions are namely high temperatures and long summers, which in combination add up to a lot of water being used overall. Once one factors in the relatively cheap cost of water, the need to be ‘waterwise’ is highlighted immensely. This can lead to easy encouragement in households to fill up the pool without much consideration of water loss and water use. However, South Africa is a water-poor country, and we face severe restrictions around pool usage.
On average, homes with swimming pools use more than twice as much outdoor water than homes without swimming pools. And whilst many homes across South Africa have swimming pools, being equipped for the warmer climate, this entails high water usage. SA Pools has put together this handy fact sheet to advise on various ways to minimise the water use of arid zone pools.
While most of us know the term from boiling water and seeing it turn into steam, a simple definition of evaporation is the process whereby liquid water becomes a gas and dissipates as the water temperature is increased.
During summer, evaporation rates increase and the water level in the pool begins to drop rapidly. In a single day, up to 300 litres of pool water can evaporate under the harsh sun, especially in the sunny country we call home. This amounts to around 30 buckets, accumulating daily from just evaporation alone. Over the period of a year, almost the entire pool volume will evaporate away if not topped up. Environmental conditions, such as humidity, wind, overnight air temperatures, and higher pool water temperature, all affect the rate of evaporation.
The size of the swimming pool in question is also a factor, with a bigger pool meaning more water loss taking place. Depending on the area, the rate of water loss varies, but a general figure of 35mm to 45mm per week during summer is the average (reference: Dr Jeremy Gibberd CSIR). This is under normal conditions, with abnormal conditions having the ability to increase water loss drastically.
Added conditions that can increase the rate of water loss include having:
Pools in open windy areas
Rim flow pools
While the average person might not know how much water flows from their backyard hose per minute, this figure works out to be around 17 litres per minute.
Topping up the pool every day, or even every second day, in summer can work out to be a lot of water. If we get into the calculations at play here, it can easily work out to be 17 litres x 30 minutes x 30 days = 15, 300 litres a month! Combine this average top-up supply with water lost through evaporation (approximately 9000ℓ per month), and your pool’s water usage could be up to 24 000 litres per month.
It is also recommended to check for leaks as this can play a significant role in increasing water usage dramatically without the homeowner even being aware. This ensures you help save the environment while saving money where you can. Undetected leaks can be hinted at by an unusual need for more chemicals alongside the obvious clue of increased water loss.
Pool covers work by insulating the pool water beneath them from both wind and heat evaporation. By making sure to cover the pool in winter and non-swimming periods, it lowers the costs of maintenance as well as the overall water loss all year around.
Using a pool cover reduces evaporation rates by 90% to 95%, making it a worthwhile consideration to keep in mind. Pool blankets and “liquid” pool covers are not as effective but do still reduce evaporation rates by over 40%.
The added benefits of covering the pool when not in use include:
Reducing the cleaning time by preventing debris from falling on the pool surface.
Reducing the amount of chemicals needed to keep the pool clean.
While it is a known fact that pool maintenance must be done regularly to make sure that the water is safe to swim in, there are ways to minimise the amount of water needed to clean the filters.
Sand filters are a popular pick for pool owners as they require backwashing once every two weeks, depending on the circumstances. It is recommended to only backwash until the glass goes clear, as backwashing for longer will waste excess amounts of water.
Other filters have the perk of being manually cleaned, which can be a preference for certain individuals. Cartridge filters are maintained by rinsing out and soaking in a solution if needed. These filters only need to be replaced every two to three years, making it a great investment in the long term.
Proper chemical balancing can prevent and cure most water clarity problems.
Pools can often go ten years without draining and refilling.
A great way to implement waterwise habits that the whole family can get into is to have waterwise rules that apply to the pool area that everyone follows. This is a great way to teach awareness of water usage and the value of such a precious resource; here’s our take on it:
No bombing or excessive splashing
Drip-dry on the top step to allow the water to go back into the pool.
Ask pool users to top the pool up with a bucket so they are aware of the amount of water being used.
Only run pool fountains and waterfalls when you are entertaining, as they increase evaporation.
Avoid overfilling the pool: the water level should be about halfway up the skimmer box opening for the filter to function properly.
Think about lowering the water level to reduce water loss from splashing.
Plant or install windbreaks around the pool as even the slightest winds, no matter how light, will increase evaporation rates.
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