While a full, healthy swimming pool is definitely the best kind of pool, there are certain circumstances where your inground pool should be drained. This is an overwhelming thought for most pool owners, but it is not that hard to DIY. Let’s talk about when, why, and how to safely drain your inground pool.

Why Drain Your Inground Swimming Pool

Let’s be clear, draining your pool is not something you should be doing very often, but even with good pool maintenance, there are times when it is called for. In fact, pool owners can expect to partially or totally drain their pool every 3 - 5 years.

There are a few common reasons to drain your pool. First, there are two different levels that creep up over time and cannot be brought back down with chemicals. Those are Total Dissolved Solids (TDS) and cyanuric acid. When TDS reaches a level above 2500 ppm, it becomes difficult to balance the water. Similarly, high levels of cyanuric acid cannot be brought down with chemicals, so pool water needs to be at least partially drained and fresh water needs to be added to bring it down. Another common reason to drain a pool is to perform repairs or remodeling, such as resurfacing the inside of the pool. Finally, in some cases, the only way to clean out very bad algae is by draining the water from the pool.

Before You Drain Your Pool

There are a few things to consider before you even think about draining your pool to avoid problems and potential damage to your property.

  1. Concrete, fiberglass, and vinyl pools all come with their own risks when it comes to draining. Knowing what type of pool you have can help you lower those risks. If you have a fiberglass or vinyl liner pool, never drain all of the water completely. Instead, partially drain the water. For vinyl pools, keep at least 12 inches of water covering the shallow end.
  2. Consider the recent weather in your area. It is best to drain your pool when temperatures are between 55-85℉. If there has been a large amount of rainfall or if rain is predicted and groundwater levels are high, it’s not a good time to drain your pool. Concrete and vinyl pools run the risk of popping out of the ground or “floating” if pressure from the groundwater underneath becomes too great and there is no water in the pool to weigh it down.
  3. Check with your city or town to find out where and when you can drain your pool water. Storm drains, home drain systems, and your own property may or may not be options depending on the laws where you live. If you drain water on your own property it needs to be done far enough away from the pool deck that it will not cause the ground to become saturated and risk the pool popping out of the ground.
  4. Allow the chemicals in the pool water to dissipate before draining, as they can be dangerous to release into the water table. Test the water to make sure it is chlorine neutral, with a neutral pH.
  5. Turn off the electricity on your pool pump and pool light.

How to Drain Your Inground Swimming Pool

  1. Use a submersible pump to drain your pool. Never use the pool pump, as this will cause your pump to draw in air as soon as the water level gets below the skimmer. This can result in a burnt out pool pump that is broken beyond repair.
  2. Keep a close eye on the flow of water and the positioning of the drain pipe during the entire process to avoid misdirected water and flooding.
  3. If you are draining an extremely green or stained pool, hose down the pool walls as you go to avoid letting them dry. If the algae dries on the walls, it will be much harder to clean later.
  4. When the pool is mostly drained, open the hydrostatic relief valve in the main drain and the hydrostatic relief plugs located on the floor of the pool. They allow groundwater to come into the pool when it is drained, releasing the pressure and preventing the pool from popping out of the ground. Opening one or two should do the trick.
  5. If you drained the pool for repairs or remodeling, get it done as quickly as possible. The less time your pool is empty, the better.
  6. Replace the hydrostatic pressure relief valves. It is quite common for them to break during removal, so install new ones, if necessary.
  7. Refill the pool with fresh water using a garden hose. Use more than one hose if available.
  8. Reattach the pool cleaner and turn on the pool pump so the filtration system can start doing its job again.
  9. Balance the water. Use a handy pool start up kit to get your sanitizers and other chemical levels within the optimal range.

Draining Your Above Ground Pool

Draining an above ground pool is sometimes necessary due to an extreme algae bloom, poor water quality, or to perform repairs. For pools with a vinyl liner, it can be tricky to avoid wrinkling or tearing the liner, so be extra careful to pull out wrinkles during the refill process.

  1. To drain your pool quickly, use an electric submersible pump. Another method is to create a siphon with your garden hose, but it will take much longer. To do this, connect the end of the hose to the faucet and put the other end in the pool. Turn the water on so it flows into the pool. Detach the hose from the faucet and immediately lower it to the ground so that the water starts to flow out of the pool.
  2. Always drain the water far away from the pool area to avoid saturating the soil underneath. Again, consider local regulations when you decide whether to discharge the dirty water into your home drainage system, a storm drain, or your own landscaping.
  3. Unless you are replacing the liner, leave about six inches of water in the pool. Scrub the pool walls, perform repairs, or treat the water.
  4. Refill the pool as soon as possible using your garden hose.

When it comes time to drain your inground pool in order to bring water quality back to desired levels, being prepared and working quickly will give you the best results. If you have questions about draining your swimming pool, or about any of our pool products, check us out online at doheny.com or give us a call today at 800-574-7665.