Pool Overflowing from Rain? Expert Tips & Solutions to Prevent Damage

Depending on where you live, heavy rainfall may be a common occurrence. When storms hit, the flow of rainwater into your pool might be so great that your pump can’t remove it quickly enough to prevent it from overflowing. That might not be serious, but it could also have disastrous results for your pool, garden, and home. What can be done if your pool is overflowing from rain?

If a pool overflows with rain, the chemical balance of the water is affected, making it unhealthy and unsightly. Depending on how it’s handled, the overflow can kill the surrounding lawn and plants, damage the pool deck and paving surrounding the pool, and even affect the structure of your home.

Logic tells us that if water flows into your pool at a greater rate than it can be pumped out, it will overflow. But that’s not necessarily the case. Several steps can be taken to prevent a pool from overflowing. If it does, there are ways to avoid severe damage being done. When you know the cause of the overflow, the remedies become a whole lot clearer. So read on!

Pool Overflowing From Rain – Reasons, Results And Remedies

Of the many pools I’ve maintained, only one had an overflow problem that threatened to cause serious damage. What makes some pools more problematic than others?

Why Is My Pool Overflowing?

Water flowing into your pool is either directly from the rain, which needs to be torrential and of long duration to really cause a problem, or from run-off.

You Might Have Overfilled Your Pool

A full pool looks great, but it may result in overflow with even moderate rainfall. You should keep the level between one-third to one-halfway up the skimmer box – that will give enough capacity to allow for at least six inches of rain to fall and will also enable the skimmer to effectively remove floating leaves and debris from the surface.

The Positioning Of The Pool Might Be The Problem

My one problem pool was situated on the lower terrace of the garden, and apart from being totally exposed to the rain, it also had surface water streaming into it from the surrounding ground. If your pool is in the path of run-off water, it’s going to overflow unless you divert it.

The Pool Surround May Be Incorrectly Laid

A common fault with many pool surrounds is that they don’t have built-in drainage and often slope towards the pool instead of the other way. As a result, not only do they feed rainwater into the pool, but they also prevent overflow from draining away.

Your Pool May Not Have An Overflow

Almost all modern pools have an overflow drain just below the rim, but some older pools were built without one. An overflow drain may be connected to a storage tank, lead directly to a municipal stormwater drain, or lead to the street gutter. The worst situation is when the overflow pipe is left to discharge into the garden, as this may damage plants and lawns.

Even if your pool has a drainage system, there may be times when the rainfall is heavy, and so prolonged, that it simply can’t handle the amount of water flowing into the pool.

Possible Results Of Your Pool Overflowing During Rain

It’s not always a disaster when your pool overflows, but here are some of the possible results:

  • The chemical balance of the pool water is altered by all the additional rainwater. Firstly, It’s diluted by the rain, which may be slightly acidic, so the pH, chlorine, and stabilizer levels can all be affected. Add to that the contaminants and dirt washed into the pool, and you could land up very soon with a green, unhealthy pool.
  • The overflowing pool water can get under your decking, causing the wood to get soaked unless it’s well-protected, with possible damage becoming visible in the days ahead. If the water erodes the ground under the pool surround, it could cause a partial collapse of the paving and an expensive repair.
  • When the water level is at the top of the skimmer box, the leaves and debris can’t be removed. This can result in the drain in the pool floor getting clogged and the whole filtration system being affected.
  • If flooded by pool water, your garden can be badly affected, as lawns and many plants can’t survive the chemical content of the water.

How To Stop My Pool From Overflowing During Rain

While you can’t do anything about the rainfall in your part of the world, there are steps you can take to prevent your pool from overflowing and causing the kind of damage we’ve mentioned.

  1. Keep an eye on weather forecasts and prepare your pool by pumping out an amount of water that will compensate for the inflow. Dropping the level by 3 to 5 inches will handle most overflow risks.
  2. An expensive but effective solution is to install an overflow drainage system around the perimeter of the pool. This consists of a strip drain or channel which prevents overflow from spreading and carries it away from the pool area into a storage tank for later use, into a French drain, or into the property’s main drain.
  3. Use your pool pump by setting the multiport to waste and pumping out sufficient water to bring it down to the correct level. Keep a close watch on this as the level drops quickly, and you don’t want to take it too far. Also important is to release the water into a drain or tank and not directly onto the garden, which will do the damage you’re trying to avoid.
  4. If, for some reason, your pump is not working (power may be out In a severe storm), you can use your garden hose to siphon water from the pool – it’s a relatively slow process, but it works. Again, remember to lead the hose well away from the pool and preferably into a drain.


Finally, when you’ve controlled the overflow, and the rain has stopped, you’ll need to check the chemical balance in your pool and correct it. You might give it a shock treatment if it has already started to turn green because of all the contaminants introduced into the pool. The heavy chlorine content will kill off any algae, and you’ll have a sparkling pool again – till the next storm!