How To Drain, Flush & Refill Your Hot Tub

Hot tubs need regular maintenance to ensure the water is kept clean and safe for bathers. Whether you are running on chlorine, bromine, ozone or you have a salt system, you should drain and refill your hot tub peroidically and flush the pipes to keep them clean. In this guide we will explain why hot tubs require draining, how to drain your hot tub, how to clean the pipes and how to refill it. We will cover the key topics and questions around this process to make your hot tub maintenance a breeze!

Why Do I Need To Empty My Hot Tub?

One level that you may not have heard of and one that is very rarely tested in domestic hot tubs is TDS (Total Dissolved Solids). This measures everything that is dissolved in hot tub water including chemicals (PH balancers, chlorine, bromine etc), organic matter from bathers and anything else that has found its way into your hot tub water. When TDS gets too high the water is very saturated and becomes difficult to work with. With high TDS you may experience some of the following:

Unable to balance PH.
Using lots of chemicals.
Water smells or is tinted.
Scale buildup on the hot tub.

Although there are ways to prevent TDS getting too high, once it is high and you are experiencing some of the above issues, the only way to reduce TDS is to drain and refill your hot tub with fresh water. This is why the general recommendation is to drain your hot tub every 3-4 months to prevent the TDS from ever getting too high.

Another reason you need to drain your hot tub is to flush out the pipework and ensure a good deep clean. This will be explained below.

How To Drain a Hot Tub

There are two main ways to drain your hot tub - using your hot tub drain valve or using a submersible pump.

Using Your Hot Tub Drain Valve

The slower method of the two is to use your hot tub drain valve. These are conveniently plumbed into your hot tub and therefore are probably the easiest way to drain your hot tub.

Follow the Pipe Flush process prior to draining.
Turn the power to your hot tub off at the circuit breaker. Pumps and jets should not run while there isn’t any water in the spa as this can cause damage to components.
Next, find your drain valve, usually situated at the bottom of the main panel on your hot tub but also sometimes on a corner. Your hot tub may have two valves, a primary and auxiliary. Use the primary to drain most of the water, and then open the secondary to drain the internal bleedlines (particularly important for winterising).
Attach your garden hose to the drain valve if necessary. Run the hose downhill or on level ground out to your drain. It’s best to transport the water to an existing drain, to avoid damage to your lawn or patio.
Open the ball valve on your spigot so the water can drain.

How to Drain a Hot Tub with a Submersible Pump

Want to drain your hot tub faster? A submersible pump can drain a hot tub in as little as 10 minutes depending on size.

Follow the Pipe Flush process prior to draining.
Turn the power to the spa off at the circuit breaker.
Place your submersible pump in the hot tub footwell or deepest point.
Run the hose to your drain.
Turn the pump on and let the spa drain.
When the hot tub is empty, turn off the pump, remove it from the spa, detach the hose, and return it to storage. Please note that some pumps have float switches so will cut off when the water goes below a certain level.
To be sure no dirty water residue is left in the pipes you can either use a wet and dry vacuum on the jets or run the hose through the jets to clean them out.

How to Flush & Clean Your Hot Tub Pipes

While you are draining your hot tub, it is a good time to purge your plumbing lines with a pipe flush/cleaner to remove any biofilm or bacteria that may have built up in the pipes. Ensure you follow the specific instructions of each product but the below gives a basic general guidance on using a pipe cleaner in a hot tub.

Remove your hot tub filters.
Turn your jets on full.
Pour the suggested amount of pipe cleaner into the filter housing.
Allow the jets to run for 15-30 minutes.
Then follow the "How To Drain a Hot Tub" procedure above.

How to Refill Your Hot Tub

After draining your hot tub, use a clean soft cloth to wipe the shell and filter compartment down. Now is also a good time to clean your hot tub filters.

Refilling your hot tub is very simple. Place your hose in the filter housing and turn it on. Fill through the filter housing to fill the pipework first and reduce the risk of an air lock. An air lock is where air is trapped in the plumbing lines and does not allow the water to flow properly, your system may show a "flow" error when this occurs. Contact your dealer if unsure.

FAQs

Can You Drain Hot Tub Water on Grass?

Hot tub water is very unlikely to damage your lawn but if you are concerned or have a newly set or delicate lawn then it is good practice to not add chlorine for a period and allow the chlorine to level to drop to near 0 before draining the water onto your grass. You can also test a small amount of water on an area of your lawn to see if it does cause damage before draining fully. If you are letting your chlorine level drop below 3ppm, do not use the hot tub and ensure you shock the water with chlorine when it is refilled.

To ensure no damage occurs it is best to drain your hot tub straight to a drain.

How to Drain Hot Tub Completely?

The only way to remove every drop of water from your hot tub is using a wet and dry vacuum. You can then suck all the water out from every jet and the small residue left in the footwell by the submersible pump. There will always be a small amount left in the pipework but this will be cleaned when you refill and dose with sanitiser.

How Often to Drain a Hot Tub?

Every 3-4 months. If your water is /blog/no-chlorine-in-a-hot-tub after adding lots, you are finding it hard to balance the PH or the water smells and is unclear then your water is probably due a change. If you are unsure, speak to your local dealer or get your water tested by your dealer.