How to drain a hot tub: a step-by-step guide

The question of how to drain a hot tub is an important one. A hot tub is a fabulous addition to any backyard, providing relaxation in the fresh air year-round, but your spa does need a little TLC from time to time. And part of this process includes removing the water.

Regularly draining the hot tub is one of the jobs that should be on your agenda to maintain the water quality. Once it's empty, cleaning is easy, and the water can then be replaced so the spa is a pleasure to step into every day. 

Whatever hot tub ideas you're adding to your outside space, our step-by-step guide, complete with plenty of expert tips, will help you keep your spa in top condition.

How to drain a hot tub in 4 easy steps

If you've recently invested in one of the best hot tubs, you might be wondering why you need to know how to empty it.

'It's important to drain a hot tub regularly for a number of reasons,' explains Sallie Leslie-Golding from BISHTA (The British and Irish Spa and Hot Tub Association). 'A hot tub is a relatively small body of water with a relatively high concentration of bathers (certainly when compared, for example, with a swimming pool). Sanitizing chemicals are added to the water to control potentially harmful microorganisms and deal with other pollutants that can enter the water during use. Over time, the water chemical balance becomes harder to manage, and it loses its characteristic sparkle and becomes lank and lifeless.'

A further reason why you should do this as part of your hot tub maintenance? 'Draining the water from the hot tub is a really good opportunity to give everything a thorough clean to keep it in tip-top shape,' says Tom Drakett-Cain of Lay-Z-Spa.

Here are the steps you need to follow to drain your hot tub.

1. Flush the pipes

'Before you drain your hot tub, it's important to make sure your pipes and plumbing are clean,' says the experts from Hydrolife.

Using an additive called a system or line flush will clean up the contaminants that build up inside the plumbing lines. Follow the pack instructions, including the recommended timings. Usually, you simply add it to the water, then turn on the jets. 'This will circulate the cleaner through all the pipework and remove any dirt or grime,' Hydrolife explains.

2. Turn the hot tub off

To drain a hot tub, you need to turn the power off by unplugging it completely or turning it off at the circuit breaker. 'If the pumps try to run whilst there's no water in the hot tub, it can cause damage to the pump and pipework,' warns Hydrolife.

3. Drain using a hose or submersible pump

'You then have two options when it comes to releasing the water,' says Hydrolife. 'All hot tubs have a drain valve which can be opened to release the water. This is an easy way to drain your hot tub which is great if you aren't in a rush.' You can connect a garden hose to the drain valve to control where it is released.

'The alternative method is to invest in a submersible pump, which is designed to pump water out quickly,' continues Hydrolife. This will usually take around 30 minutes to completely empty your hot tub.

Whichever method you choose, simply follow the steps below:

• How to drain a hot tub with a hose
  Locate the drainage valve of the hot tub. Connect the garden hose and run this to a drain. Open the valve to allow the water to drain out. Be aware that the process may take an hour or so – sometimes two.
• How to drain a hot tub with a submersible pump
  Plug in the pump, connect its drainage hose, and run this to the drain. Place the pump in the deepest part of the hot tub and switch it on. Allow to drain, but pay attention to the water level so you can switch off the pump when the water has been removed (unless it is a design that will do so automatically). After use, disconnect the hose and allow the pump and hose to dry before storing them away safely.

'Once the water has drained, you may have a little bit of water left in the footwell,' adds Hydrolife. 'This can be removed by scooping it out, or by using a wet vac.'

4. Clean the hot tub

Once the water is drained, it's important to learn how to clean a hot tub properly before refilling it with water. Use a cleaning product designed for hot tubs and follow the manufacturer's instructions. 

'The whole hot tub, inside and out, should be cleaned once it has been drained to effectively remove any dirt, grime, and bacteria lurking,' says Tom Drakett-Cain.

'Don't forget to clean the filter,' says Tim Snelling from Hot Tub Hub. 'A simple job, but often one that is overlooked and can affect the sanitation of your tub. Ensure you give the filter a deep clean when you drain your hot tub, alongside weekly rinses to ensure optimum hot tub cleanliness.' Our dedicated guide on how to clean a hot tub filter has in-depth info should you need it.

How do you fill a hot tub back up once it's been drained?

'Once the shell is clean, you can start to fill the hot tub with fresh water,' says Hydrolife. 'Keep the hot tub off and don't try to turn on any jets as the water fills the tub. One of our top tips would be to fill through the top of the filters as this will help avoid air lock in the pipes.'

According to the team, you don’t need any special equipment to fill the hot tub up, just a garden hose. They recommend filling their tubs until the top jet is covered, but below the headrest – but if in any doubt, check the instructions for your particular hot tub model.

'Once the hot tub is full, you can turn it on and then you can add a shock to the cold water, which will sanitize the water,' they continue. If you usually use chlorine to sanitize your water, you will need to use a blended chlorine shock, however if you usually use bromine, use non-chlorine shock, they add. There is plenty more info on how to shock a hot tub in our guide. Remember to test the chemical levels in the water before you get in, to check it is safe to do so. 

How often should you drain a hot tub?

Now you know how to drain a hot tub, you may be wondering how frequently you need to do it. 

'Ideally, the water should be drained every three months and refilled with fresh,' says Tom Drakett-Cain. This means that if you're using it all year long, you'll need to make sure draining is part of your hot tub winter care too.

Bear in mind that you may need to do so more frequently, however. Consider draining, cleaning, and refilling the hot tub after periods of heavy use, if the water has become cloudy or if, despite chemical treatment, the water has lost its usual sparkle.

Common hot tub draining mistakes and how to avoid them

These are the errors the experts see most often in the hot tub drainage process, and how you can avoid them:

• Forgetting to turn off the power
  Not only can leaving the power on while you drain your hot tub damage it, but it can also cause you and any other bystanders to get unexpectedly sprayed. 'As the water level drops as it's emptied, jets that are normally underwater become exposed and can spray water copiously over any unsuspecting bystanders if the power is still on, which normally serves as a fairly vivid reminder to turn the power off,' says Sallie Leslie-Golding.
• Failing to drain the water to the right location
  'Special care should be taken to ensure the water goes into a drain,' says Tom Drakett-Cain. 'The water from a hot tub can be harmful to grass, plants, animals, and insects due to the levels of chemicals in the water.' Be mindful that you should never discharge the water into a storm drain; check with your water company to be sure of where you can discharge it.
• Using the wrong tools for cleaning
  'As tempting as it seems, we would not recommend using a pressure washer to clean your hot tub filter as this may damage the filter. A standard garden hose will do the job nicely,' says Tim Snelling.