There’s a few things to be aware of if you plan on leaving your concrete pool empty. Although it can seem like a good idea to leave your pool empty after repairs, building, or for seasonal things – it’s not always the best plan of action.
Truthfully, you should not leave your concrete pool empty for more than two weeks. If groundwater is set up properly for your concrete pool it can be left empty for weeks. It’s important to make sure the hydrostatic relief in the bottom of the pool is open and functioning (it can cause issues even in an open pool). If your pool is empty during freezing weather there is a real risk of freeze-thaw damage to the surface of the pool, so you’ll want to cover it in some way (trust us, we’re the pool building experts in Texas).
Should You Empty Your Concrete Pool?
A concrete pool’s design is such that the walls and floor are held in place by high hydrostatic pressure. So when you remove the water from your concrete pool, you’re taking away the water that helps to support and protect your pool liner.
Usually when it comes to concrete pools, the water in the pool will help support the walls from collapsing. Even without the water it’s possible that the concrete will start to sag. So even though it’s in theory possible to leave the pool empty for months, we at The Complete Backyard only recommend leaving it empty for up to 2 weeks. Once you’ve drained the concrete pool, have it in mind to refill it as soon as possible. Otherwise you’ll have to replace the liner in it or possible more extensive damage.
What Happens When A Concrete Pool Is Left Empty Over Long Periods of Time
Concrete pools can last for decades with proper maintenance and care (including repairs and renovations in some cases). However, if you don’t use it for an extended period, it will start to deteriorate slowly. That’s why we ALWAYS recommend budgeting the cost of maintenance and repairs into your budget (with the right pool financing options, you’ll be able to do this easily. We talk about how to properly finance a pool here).
Something else to keep in mind is that algae will start to grow on the pool walls. Typically this is from the moisture that stays in the walls of your concrete pool, and algae are attracted to this moisture. So even with your pool empty, algae will grow and then it will be unusable when you are ready to fill it and swim again (until after an extensive cleanup anyway).
Leaving a Concrete Pool Empty During The Winter
Concrete pools are made specifically for year-round use, so it’s not always a good idea to empty yours just for the winter. In fact even in the winter, the lack of internal pressure from the pool water can still cause problems (even more so than draining it).
In Texas, we don’t deal with the frequent snow or harsh cold weather but if it is extremely cold, another option is to lower the water level in the pool so it won’t freeze entirely.
The Problems With An Empty Concrete Pool
Here’s what you need to be prepared for when leaving your pool empty for longer than ~2 weeks (sometimes it’s even less but generally, without underlying issues 1-2 weeks is fine for most pools to be left empty). The main and most costly danger is that your pool can crack. Concrete pools are dense and heavy, most weighing up to 50+ tons. Even though the pool walls are made thick, they are still subject to cracking.
An empty concrete pool during winter has to deal with the full weight of the groundwater pressure build-up below it. However, if you leave the water in the pool – it will naturally offset the groundwater pressure and prevent any extra cracks from happening. Hydrostatic pressure is what the groundwater pressure is called and it builds up in your pool walls from the ground around it. It usually only comes into factor when water levels are low or if there’s a leak in the pool. Cracks happen when the pressure (in the ground) on the outside of the pool becomes too high, and pushes into the concrete, causing damage to the walls and flooring of it.
Another consideration is any damage that was hidden before draining. If there were any leaks or cracks prior, once drained they will typically get worse. When no water is in your pool, these leaks become very apparent and can get so much worse that extensive damage is caused. So if you need to – double check your pool before draining or you’ll be pressed to get it filled back up quicker than you probably want to.
Think Twice About Draining Your Concrete Pool
A lot of the time, you actually DON’T need to drain your concrete pool. That being said, yes there are times you will need to drain it, but don’t go draining it all the time for small reasons. Draining your pool is a commitment and serious things can go wrong so be sure when you decide to empty it.
Here’s the good news for you concrete pool owners – concrete pools are the most durable so they run the least risk out of all pools of actually cracking and having damage caused to them. However, that does not make them invincible. Always try to have it drained for as little time as possible. Like we recommend, 2 weeks or less is the goal until you can fill it up again.
If your pool is extremely dirty or needs to be cleaned big time, don’t think first to drain it. A lot of the time pools can be cleaned with a little more work even with dirty water, wildlife, and more in them. You’ll also be worried about rebalancing the pool when it comes time to fill it back up.
Frequently Asked Questions About Leaving Your Concrete Pool Empty
Can an Inground Concrete Pool Collapse if Emptied?
Generally no but there are a few factors which can lead to a concrete pool collapsing. If your concrete pool is left empty for longer than 6 months, the risk of it collapsing goes up immensely. Remember, concrete shrinks when dry so in some cases, it can shrink too much and eventually cracks will build up causing the collapse.
Is it OK to drain a concrete pool?
Inground pools made of concrete or gunite are susceptible to popping out of the ground if drainage is not done properly. If there has been a surplus of rain recently or your pool is located in a wet area, it is best not to try and drain the pool yourself at all.