Most pool users take their pools for granted and enjoy all the benefits of having a swimming pool in their own backyard. That is unless you’re the one that has to maintain it! If you’re that person then you’re probably aware that keeping pool water safe and healthy requires planning, action, commitment and consistency.

That’s because pools need a delicate balance of sanitising chemicals to keep them safe to swim in. But it doesn’t take much to upset this balance – just a little rain will do it, let alone long periods of intense heavy rainfall which can be disastrous.

Rain & storms can cause a number of pool water issues including:

  • Run-off Issue – It takes just 15mm of rain over a few hours to flood a backyard. As this rain water runs through the yard, it picks up dirt and debris. If this muddy silty water starts to flow into your pool, your pool chemical balance will be immediately compromised. It only takes a small handful of dirt to increase phosphate levels enough to create algae and water clarity issues. So imagine what a continuous flow of dirty rainwater over several hours will do.

    If your pool gets contaminated with rain run-off, use a rake and slow vacuum to remove large debris. Follow up with regular pool wall brushing, add clarifiers and flocculants, and keep your pool filter running continuously. As your pool water clears up, apply phosphate remover to eliminate any residual phosphates. After your pool filter has run for 24 hours, backwash it.

  • Rainfall issues – Rain falling directly into a pool might seem harmless enough compared to run-off effects. However, rain is not as pure as you might think. Clouds might contain water vapour that is pure and distilled, but when it’s released as rain, it picks up a lot of contaminants on the way down. These contaminants include dust, air pollution (acid rain), pollen and plant spores such as the dreaded algae type. If you have overhanging trees over your pool, the rain will ‘clean & rinse’ them too and deposit the phosphate-rich contaminants straight into the pool. If you live in a built up area, acid rain can upset your pool’s water balance by diluting cyanuric acid, lowering calcium levels and lowering pool water pH.

    Before a major storm, add algaecide to prevent potential algae blooms. Test your pool water chemical levels and pH and balance accordingly.

Safeguard your pool before & after a storm

If you have fair warning before a storm hits, spend some time to safeguard your pool accessories beforehand. Safely store away all pool cleaning equipment, toys and furniture that can potentially be damaged by the weather event. However, leave your pool cover off and safely secured.

Once the storm has passed and the weather has cleared up, get to work with your pool chemicals. You’ll need to lower pool water levels, balance pool chemicals & pH, and add sanitisers. For more severe cases of contamination, you may require a pool shock application to super chlorinate your pool, and keep the pool filter operating overnight. You should also remove all large debris and correct ph (to 7.2) before pool shocking.


Protect your pool equipment from damage

Keep your pool filtration system operating during a storm. However, if flooding or a run-off threatens to inundate your pool pump and other equipment with water, shut off all power at the main power switchboard. If you can move your pump indoors or to higher ground, you can avoid irreversible water damage to your filter pump. Regular rainfall usually doesn’t affect pool equipment but flooding has more severe consequences, such as replacing your pump entirely. Other safeguard options include sandbagging your pump area and installing a lean-to over your pool equipment pad.

Improve water drainage around your pool

If you are experiencing continual run-off or flooding into your pool every time there’s a major rain event, you need to improve drainage away from your pool. Slope pool decks down a ¼ inch away from your pool to direct rain run-off directly into your grey or storm water drainage system.

During heavy rain events, work out how and where rain run-off goes in your backyard, especially around your pool. You can easily change the slope of your yard to change the path of the run-off. Find the high and low spots in your backyard and reverse them. Grade the slope in the right direction so that water can flow into a drainage path away from the pool. You may have to install extra drains to connect up with your main drainage system.