There are several risks associated with draining a pool, let alone letting it remain that way, and the consequences can extend across structural and safety hazards. If you’re thinking about draining your swimming pool, you’ll need to make sure you do it correctly and should know how long you can leave it empty.
In this post, I’ll discuss how long you can leave a pool empty and other important points, such as how to clean a pool without draining it, when it’s okay to drain, and the best way to do it. So, let’s right dive in!
- Leaving a pool empty, whether inground or above ground, can have severe short-term and long-term consequences.
- The best season to drain a pool is during mild weather—not too cold, not too hot!
- Draining a pool is a last resort step since most problems can be resolved without complete drainage.
How Long Can You Leave a Pool Empty?
The short answer is: not for very long. How long you can leave it empty depends strongly on the type of pool, the climate, and groundwater and hydrostatic pressure. However, as a general rule, the longer you leave the swimming pool empty, the more likely you are to deal with severe short-term and long-term consequences.
Type of Pool
For instance, inground pools, especially those with vinyl liners, are much more susceptible to damage since the liner will shrink and wrinkle without water. On the other hand, concrete pools are much more resilient than fiberglass or vinyl pools.
But with that said, concrete pools can crack and “pop” out of the ground entirely if the underlying groundwater pressure is high enough. This is because emptying a pool causes an increase in the hydrostatic pressure extended by the groundwater—especially in areas with a high enough water table. This pressure easily causes major damage to the structure of the pool.
If groundwater is not an issue, the pool can be left empty for much longer. But then, you still have to consider the climate. Leaving a pool empty during the cold winter season offers a real risk of freeze-thaw damage to the structural integrity of the pool surface.
As you can see, there is no straight answer in this situation. You have to weigh the risks and benefits of emptying your pool. Draining a pool is definitely not a decision to take lightly. Usually, I recommend only draining the pool if you absolutely need to for cleaning or repair work. And if you absolutely must, keep it empty for as short a period as possible.
Why a Pool Should Not Be Empty
Let me reiterate: I do NOT recommend leaving the pool empty. Doing so opens the pool up to a whole host of risks and issues. Here’s a quick overview of why it’s not a good idea to leave the pool empty:
When a pool is full, the water within exerts pressure against the groundwater below the structure. This balance is disturbed when you drain a pool, which can cause major structural damage, such as cracking, shifting, or even a pool popping out of the ground entirely.
Vinyl Liner Issues
Pools with vinyl liners are particularly vulnerable to damage when left empty. As I mentioned, liner shrinks and wrinkles or even cracks in the absence of water. Replacing one is a costly and time-consuming affair, so just don’t do it!
Collapsation Risk (Above Ground Pools)
The weight of water is crucial for stabilizing an above ground pool and preventing it from toppling because of strong, heavy winds. When left empty, it may collapse.
Long-term exposure of the pool’s surfaces to sunlight without water accelerates the degradation of the pool as a whole. This is especially the case for pools with surfaces sensitive to UV rays, such as plaster, which is made to stay underwater at all times.
For all these reasons and more, I always recommend consulting an expert before you drain your pool. An expert will be able to assess your pool type, local conditions, area regulations, and your reasons for drainage to better assist you. Even better, hire a professional to do it for you. One little slip-up and your pool may be damaged beyond repair!
Can You Leave an Above Ground Pool Empty?
While it’s generally easier to leave an above ground pool empty for a short time, I do not recommend it either. Most above ground pools rely on the weight of the water to be stable, which helps prevent the pool from collapsing. An empty pool means structural integrity is compromised, especially since the water is not adequately supporting the walls.
Another issue is that even though the pool might only be partially embedded in the ground, pressure from the surrounding soil might still cause the pool walls to buckle or lean. In areas with particularly high groundwater levels, the pool might even lift off the ground! Plus, the vinyl liner of an above ground pool shouldn’t be exposed directly to the sun.
In short, while leaving an above ground pool empty may not be as risky as it is with an inground pool, you should still proceed with caution. Always double-check with a pool professional before draining your above ground pool.
Of course, the exception to this is an inflatable pool, which you can easily deflate and put away for the season after draining!
How to Clean a Pool Without Draining It
Before you get started, make sure you have the right materials on hand:
Cleaning a pool without draining is easy if you follow the right steps. Here’s a quick rundown.
- Brush the pool’s walls from the shallow to the deep end, wall to wall, with steady, even strokes.
- Use a skimmer net to scoop up pieces of debris.
- Vacuum the pool. You can either manually vacuum or use an automatic cleaner. Clean the filter when you’re done.
- It’s now time to balance the pool’s chemistry. You’ll need to balance the pH (7.2 to 7.6), alkalinity (80 to 120 ppm), calcium hardness (175 to 275 ppm), chlorine (1 to 3 ppm), and cyanuric acid (20 to 50 ppm).
- If chlorine levels are really low or the pool is still dirty, shock the pool to flush out any lingering contaminants.
When Is it Okay to Drain a Pool?
As a general rule of thumb, you should avoid completely draining your pool if possible, as it can cause expensive repair work down the line. In fact, even if you have to drain it for water quality reasons, I recommend only partially draining and refilling the pool rather than emptying it completely.
Complete pool drainage is only okay in the following situations:
- High TDS (total dissolved solids), CYA, or calcium levels
- Acid washing
- Refinishing, replastering, or repainting
The Best Season to Drain a Pool
The best season to drain a pool is during mild weather. Not too hot, not too cold. Periods of temperature that are too extreme can affect the pool poorly and cause cracking to occur in the liner or concrete. So, for this reason, if you must drain the pool, I recommend doing so in the spring or fall (ideally in the spring). However, If the temperature climbs above 85 degrees Fahrenheit at any point in the process, postpone the draining! The same applies to temperatures near or below freezing.
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Frequently Asked Questions
How long can pool plaster be without water?
It’s unsafe to leave pool plaster without water for an extended period. Never leave a pool plaster without water for anything longer than a week. Pool plaster is meant to be underwater, so you risk the plaster drying out and cracking even with short-term exposure.
Can I leave my inground pool empty over winter?
No, absolutely not! Instead of draining over the winter, which will seriously damage the pool, winterize it properly to keep it safe from debris and harsh weather.
Is an empty pool a safety hazard?
Yes, an empty pool can pose safety hazards, as it can cause serious structural damage, including the land around the pool area. Plus, an empty pool can also lead to standing water, which is a breeding ground for mosquitos.
Approach Draining a Pool with Caution
I hope I have sufficiently warned you against draining your pool. As you no doubt know by now, draining a pool is an absolute last-resort step. Most pool issues you come across can be resolved without completely draining the pool. So, only drain your pool if you absolutely must, and always check with an expert before you do so. In fact, I recommend having a professional drain your pool for maximum safety and effectiveness.
Do you have more questions about draining a pool or other pool-related topics? Drop me a message!