How To Drain A Pool: Draining An Inground Pool (In 7 Steps)



Swimming pools should always be clean bodies of water that are ready for swimming at the drop of a hat.

But at times, issues with the water or even the pool itself  can creep up, requiring you to empty out the entire structure.

Draining an inground pool can be… well, draining. It’s a big job to remove all of the water (and refill it), so let’s take it from the top.

Before You Start Draining The Pool

Preparing for your drain should consist of the following steps:

Calculate The Costs

Understand that the price of doing a pool drain is considerable. Not only do you have to pay to run a pump that empties the pool, but you also have to shell out for the water that’s required to fill it back up.

Most households average anywhere from 80 to 100 gallons of water usage per day. Comparing that to a modest swimming pool size of 10,000 gallons, you can count 100 days of your daily water use to get an idea of how much the refill bill will be. 

Clear Your Schedule

You’ll need to set aside a block of time to do the drain uninterrupted, so don’t schedule anything of importance for a good 2 to 3 days. This isn’t a job where you can “set it and forget it”. Plan to stay close to the pool in case of any unforeseen events that may arise.

On average, the drain alone can take between 8 and 14 hours. This, of course, depends on your pool size and drain rate produced by your pump.

Refilling the pool can be even more time consuming. The average spigot moves anywhere from 4 to 12 gallons of water per minute (GPM). Again, depending on your pool size, it might take up to 2 days just to refill the pool.

Check The Weather

While it might sound like a good idea to do a drain on a sunny day, that’s not actually ideal. Pools are designed to be filled with water. Having them sit empty in the hot sun can dry out the finish/liner and lead to damage.

The best time to do a drain is in weather under 85°F, and if possible, during the cooler months. The end of pool season (September/October) is popular for this reason. 

Additionally, you need to keep on top of the weather forecast so you avoid draining during a stretch where there will be, or has been considerable rain. An empty pool has no water to keep it weighed down. When it rains, water is absorbed into the ground.

The result can be a pool structure that literally gets pushed up and out of the ground. Obviously, this would be pretty catastrophic, so you need to ensure you drain during a period of cool and dry weather.

Check Your Chemistry

It may sound counterintuitive because you’re literally dumping out dirty water, but you need to make sure the water chemistry is balanced.

In fact, many cities require this so you aren’t adding high levels of harmful chemicals to the environment. So break out the testing kit and get the pH level, alkalinity level, and chlorine level nice and neutral before you begin your drain.

Check Your Equipment

The drain and refill needs to go off without a hitch, so ensure that all your pool equipment is turned off.

Some pools are set up on automated timers, which is great for when it’s in use, but can be a potential nightmare when there’s no water in the pool. 

Items like the pool lights and pump depend on the water to keep them cool when in operational mode. Pool lights will shatter if they’re left on when water isn’t present, and the pump can take on air which will damage it.

Plan The Exit Path

Correctly disposing of the water is crucial.

You’ll need to check your city’s regulations to find out where it’s safe and suitable to send the pool’s wastewater. Directing the water into a sewer or storm drain is most common, so make sure you have a hose that’s long enough for the job.

You never want to empty the water somewhere on your lot as it can seep into the ground and potentially pop the pool.

Also, directing the hose downslope will help to reduce pooling of the water. This can occur if there’s a clog somewhere down the line.

How To Drain An Inground Pool (7 Steps)

Here’s our easy, 7-step guide you can use when you need to do a drain.

Step 1. Get A Submersible Pump

While some people recommend you use your pool pump to drain the water, we highly recommend NOT doing this.

This method sucks water out of the pool via the skimmers and main drain(s). But once the water falls below the skimmer level, the skimmer will still try to suck in water. In reality, it will just keep sucking in air, and the probability of that air damaging your pool pump is extremely high.

Instead, use a submersible pump to drain the pool. These pumps are available for rent or purchase (buying it will set you back around $150).

Place the pump in the deep end of the pool. Make sure you have an electrical cord that’s long enough to reach a power outlet in your backyard, and attach a hose to the pump that’s long enough to empty out into the sewer you’re using as your drainage point. 

Step 2. Drain The Pool

This is as simple as turning on the pump to siphon the water from the pool.

Keep a close eye on how the drain is going throughout, making sure the hose stays connected to the pump, and water easily flows into the sewer/drain with no pooling issues.

Don’t forget to double check if draining into the sewer is legal in your city!

Step 3. Open The Relief Valves

As you get close to the end of the drain, open up the hydrostatic pressure relief valves on the floor of the pool. By doing so, you’ll let any ground water swell up into the pool.

This protects the pool from popping out of the ground. Some finishes like plaster may be covering the valves. This will require you to use a hammer and chisel to remove plaster so you can unscrew the valves.

At this point you’ll also notice there’s a small puddle of pool water remaining that couldn’t be pumped out. This is of little consequence in the way of total dissolved solids (TDS), as the addition of clean water will dilute it to very low levels.

Step 4. Do The Work

With the pool now empty, the time is right for doing any painting, repairs, acid washing or resurfacing.

Try to do this as quickly and efficiently as possible so the pool isn’t sitting empty for a long period where the finish can dry out and become damaged.

Step 5. Close The Relief Valves

With the work done, close the relief valves you opened in step 3.

It’s always a good idea to have backups in case any valves were damaged when you opened them. Remember to use teflon tape around the threads for a tight seal.

Step 6. Fill ‘er Up!

Using a hose connected to a backyard spigot, lay it into the pool and turn on the water. If you can use more than one spigot and hose simultaneously, you’ll significantly reduce your fill time.

Step 7. Pump & Balance

Once the pool is filled up to the halfway mark on the skimmers, you can shut off the water and remove the hoses from the pool.

Turn on your pump, and then add the necessary chemicals the water requires for sanitation. Test your water until it is properly balanced, and you’re all done!

When Should You Drain A Swimming Pool?

Draining a pool should always be a last resort, so be absolutely certain you’ve exhausted all avenues when it comes to water balancing or repairing broken areas of the pool.

Ideally, once you’ve filled it up with thousands of gallons of water and added all the necessary sanitizing chemicals, you should get at least 5 years of use if practicing proper pool maintenance.

Typically, these are the scenarios when draining is necessary:

If The Water Needs To Be Changed

At some point, the pool water will have to be changed out. There’s no way around this, but waiting until the last possible minute will save you the work and costs associated with draining and refilling a pool multiple times.

Issues like green pool water, high levels of calcium or cyanuric acid in the pool may require a partial drain to dilute the water. This isn’t half as labor intensive or costly as a full drain. Additionally, you may still be able to rectify some of these water issues through the addition of certain chemicals.

After a few years though, the level of TDS in the water will be too high to ignore. Total dissolved solids are exactly what it sounds like – they’re a record of everything the pool water has dissolved.

Measured in parts per million (ppm) with a digital tester, TDS levels should become concerning around the 4000 ppm mark. For reference, drinking water has roughly 500 ppm, whereas ocean water is closer to 30,000 ppm.

Most water issues can be rectified by adding chemicals, but the only way to get rid of high levels of TDS is by doing a drain. There’s no way around this unfortunately, as the addition of more chemicals will only increase the already high TDS levels.

Things you’ll notice when TDS gets too high include an increased consumption of sanitizing chemicals, and the appearance of stains on the pool’s finish due to the oversaturation of minerals in the water. If high TDS levels aren’t dealt with, they can even cause the finish to erode.

If Certain Parts Of The Pool Need Repairing

Just like any other area in your home, repairs to the pool are inevitable. But when they’re necessary is another matter altogether.

If your pool has a vinyl liner, you may start to notice it bulging and fading over the years. You may even pick up a tear or two. These can be patched up using an underwater patch kit, but eventually you’ll need to replace the liner.

Damages on the pool finish can also occur in the form of chipping (if you have tiles) or flaking (if you have plaster). Pools that are made from gunite or shotcrete can also develop cracks and leaks which can lead to serious issues if left unfixed.

If The Finish Needs To Be Cleaned

If your swimming pool goes years without being thoroughly scrubbed, it’ll catch up with you eventually. Yes, you should still be following a maintenance schedule using your skimmer net, pool brush, and vacuum, but the presence of TDS in the water will compound as time goes on, staining the finish.

Pool water can become high in metals or calcium, both of which will leave permanent reminders on the walls of the pool. In some cases, calcium deposits can even affect operation of your pool equipment. That’s a bill you can live without!

To fully remove surface stains, you’ll need to do an acid wash that requires an empty pool. 

If You Want To Paint The Pool

Some pool finishes are absolutely bare bones, simply having a coating of epoxy paint over their concrete shell.

Due to the amount of harsh chemicals and sunlight, the painted finish on these pools will eventually begin to fade and need a fresh coat.

Some people will even go so far as to repaint their plaster pool finishes, but resurfacing this type of finish is more cost-effective over the long term.

If There Are A Combination of Things

Waiting until it’s absolutely necessary to do a pool drain has a hidden advantage – you can do multiple things to the pool all at the same time.

Repair structural issues and then acid wash it. Replace a vinyl liner that’s about to give up the ghost when doing a water swap. If you can time things right, you’ll save a lot of money by tackling multiple issues during a single drain.

We’re Pulling The Plug!

Emptying a swimming pool is serious business, and because of that, it scares many people off from doing it themselves.

By following our guide on how to drain a pool, you no longer have to be intimidated by this process, and you can turn over your water without having to pay an expensive professional to do the reset for you.

Categories: Pool Care, Pool Problems