When Should I Drain My Swimming Pool?

Draining a pool is a big task that not only takes a while but will also cost you a lot in water bills when you eventually refill the pool. Luckily, this task doesn’t have to be done often, but there are certain cases when fully or partially draining your pool is necessary to repair parts of the pool or fix the chemical balance of the water.

In this article, I will break down some scenarios when you will need to drain your pool and describe the best way to do it safely.

Main Takeaways

  • It isn’t usually necessary to drain your pool fully. If you have to drain the water for water quality reasons, you typically only have to partially drain the water.
  • You should avoid draining your pool in temperatures above 85 degrees or temperatures below freezing.
  • Always check your groundwater levels prior to draining your pool to avoid expensive damage to your pool’s structure.
  • Consult a professional if you are not comfortable. It is always cheaper to pay an expert than repair costly damages because you were unprepared.

When and Why a Pool Should Be Drained

Most pools rarely need to be drained. Because draining a swimming pool without damaging it can be difficult, experts have figured out ways to do most necessary work without removing all the water. However, there are a few reasons why you might have to drain your pool:

  • Total dissolved solids levels
  • Certain types of repair work
  • Refinishing and/or repainting

Total dissolved solids (TDS) are substances that accumulate in the pool water over time. Eventually, they cause water chemistry to become very unstable. This means more and more chemicals are required to maintain your pool water within the correct parameters. However, it is not always necessary to drain the pool entirely to deal with this problem.

If your pool requires certain types of repair or refinishing, we will take care of the drainage process. This is often the best idea because draining a pool improperly can damage it. If you will be repairing or refinishing the pool yourself, educate yourself on the process for your specific type of pool.

What Time of Year is Best to Drain a Pool?

Depending on the type of material your pool is made of, exposure to the elements may damage it. Because of this, the best time to drain your pool is when the weather is mild. If the temperature is over 85 degrees at any point in the process, it is best to postpone. The same is true of temperatures near or below freezing.

Because of these temperature parameters, the best time of year to drain a pool is usually in the spring or fall. Spring can be a good option because the fresh water will be ready for summer swimming. Fall can work, too, but most professionals do not recommend letting your pool remain empty over the winter, so you will need to at least partially refill it.

Why You Should Periodically Drain Your Pool

The most important reason to drain your pool is to deal with TDS levels. When TDS levels get too high, they start to interfere with the chemicals at work, keeping the water sanitary and clear. More and more chemicals are needed, which can be harsh on the skin and even damage the pool itself. Eventually, a point is reached where the water cannot be adequately maintained, no matter how many chemicals are used.

Most professionals recommend draining your pool every three to five years to keep TDS levels low, which I agree with. How often your pool needs to be drained depends on several factors, including overall use. If the pool is partially drained every winter, this dilutes TDS levels and will extend the interval between complete water changes.

How to Drain Your Pool

Before draining your pool, the groundwater levels should be considered. If water levels in the area are high enough, they can cause your empty pool to pop out of the ground. In addition, fiberglass and vinyl liner pools require special treatment because they are typically not built to be drained entirely. Completely removing the water from these pools can cause bowing or cracking of the surface.

Once you have assessed the groundwater situation and the needs of the type of pool you have, the safest way to drain your pool is to use a submersible pump. These can often be rented from pool supply companies or hardware stores. While the filter pump can be used to drain a pool, this runs the risk of damaging an expensive piece of your pool hardware.

Usually, pool water must be drained into the sewer outlet on your property. Sewer lines are not built to deal with huge quantities of water all at once, so the outflow should be kept to approximately 12 gallons per minute or less. Completely draining a pool with a garden hose can take a day or more. In most cases, it will need to be at least partially refilled, so you can plan on the process taking a couple of days to complete, at the minimum.

You might need to fully or partially drain your pool for several reasons. However, it can be a big task, and doing it improperly can result in unwanted consequences. A little planning ahead can save you from a big headache later.

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Risks of Improperly Draining Your Pool

There are a few risks:

  • The pool can heave out of the ground
  • Sun and exposure can damage your pool
  • You can damage or burn out your filter pump
  • You can back up the sewer system into your home

Your pool heaving out of the ground is a serious problem that may occur if the groundwater level in your area is high. This might be the case all the time or only after several days of heavy rain. The problem occurs when your empty pool starts to float on the groundwater and be lifted from the ground.

Empty pools are also susceptible to damage from exposure. Vinyl pools tend to contract when emptied, which can result in damage when they are refilled. Gunite or fiberglass pools can crack, and fiberglass pools may suffer bulging or splitting if drained. It may also void your warranty to drain your fiberglass pool.

If you do not correctly adjust your filter, pool pipes, and waste lines, you risk damaging or burning out your pool’s motor. This can happen if the gallons per minute (GPM) of your pump exceeds the ability of your waste line to handle it. It can also occur if the filter sucks in air and runs dry. If that happens and you need to replace the unit, read my research on top-rated pool filters and top pool pump brands for specific recommendations.

Most municipalities do not allow you to dump pool water just anywhere. The approved location is usually your sewer system. However, putting too much water into your sewer system all at once can result in it backing up into your home.

When to Consult a Professional

If you are not 100 percent certain that your pool needs to be drained, you should consult a professional. Many pool repairs can be done underwater, and many problems with the water can be treated rather than requiring replacement. If you do not know what the water table is in your area or are not entirely sure you know how to drain your pool, talk with a pool pro who can help.

When you need to fill your pool back up, head to my article on pool water delivery and other options.

Questions about draining your pool? Let me know, and I’ll be glad to help.

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