Step-by-Step Guide to a Hot Tub Drain and Refill

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As a hot tub owner, you should be able to perform a standard hot tub drain and refill. It’s typically required anywhere from every 3-4 months, less frequently if you’re able to keep your hot tub chemistry balanced at all times. A refill is a great way to get your hot tub clean and reset your system if it has become chemical rich or difficult to keep balanced. Here’s HTW’s steb-by-step guide to draining and refilling your hot tub.

1) Before you drain the hot tub, take this time to purge your system. Adding a product like SeaKlear Spa Safety Flush will get any accumulated organic matter out of the plumbing and prevent you from having any persisting water chemistry issues.

Add SeaKlear to water, about 8 oz. per 400 gallons of water (or 4 T per 1—gallons). Run the jets, blowers and other water features on high for 15-30 minutes to cleanse the system.


2) Turn OFF the power to your unit. You should always exercise safety when dealing with something that plugs in. The electricity and the heating unit should be off completely.

3) Take out the filters at this time and clean them with a hose and let it soak in filter cleaner.

4) Drain the hot tub.  There are two different methods of draining a hot tub, depending on your hot tub unit. If you have a hot tub with a gravity drain/plug system (could be either along the base of the unit or inside an outer panel—refer to your owner’s manual), remove the cap or plug and hook up a hose to the opening if you want to redirect the water elsewhere. If your hot tub is on a wood deck, you probably don’t want the water emptying over any treated wood.

Hot tub water can be used on lawns and in flower beds if it hasn’t been hyperchlorinated (shocked) the night before. Some cities (like Las Vegas) require you to empty the water into the city’s drain system so check your local ordinances to make sure you’re complying.


Some hot tub units don’t have an exterior drain because they are prone to cracking and leaking water. In this case, use a standard hose to siphon out the water or run a sump pump to empty the hot tub. A quality sump pump typically only takes about 10-15 minutes to empty the tub.

Don’t leave a sump pump to empty the hot tub without attending it. If it continues to run without water, you could burn out the motor.


5) Once your spa is empty, take the opportunity to give everything a good clean. (If you haven’t already, remove your filters and get them cleaned.) Use a specialty cleaner like Gel Gloss or Fast Gloss to clean the surface of your spa—normal household cleaners aren’t approved for use on hot tubs. Harsh cleaners can potentially take the finish off the acrylic, leaving them porous and susceptible to allowing dirty, film, and girls to penetrate the once-solid surface. Household cleaners also increase the likelihood that your hot tub will have a foaming problem upon refill. If you have calcium build up, scrub with a nylon brush. You can use baking soda as a non-abrasive cleaner to get off grime and calcium deposits.

6) Rinse off the surface of the shell after it’s been cleaned to remove any residual cleaning product. Pump out the accruing water.

If you’re draining the hot tub for several months, keep your filters indoors so they don’t get any unnecessary wear. Drain the lines by blowing out the water with a wet/dry vacuum so that no water is left in the plumbing that can lead to damage. Once empty, Leave your drain open to prevent freezing/cracking.


7) If you are going to refill the hot tub, replace your filters, plugs, and caps on all the drains.

8) If your local water is mineral rich (which often results in calcium hardness in the water), use a pre-filter on the end of your hose. These make your water much more mineral-neutral upon filling, thus making it less tricky to balance afterward.

Before you add your pre-filter, flush out the hose for 30 seconds to eradicate any water that has been standing still in the hose.


9) Refill with the hose pointed down the center of the standpipe in the filter compartment. This will reduce airlocks in the equipment and the water will circulate through the heater.

NEVER refill your hot tub with hot water—this will affect your sensors and send your electrical system on the fritz.


10) Turn the equipment back on once the spa is full (about 1 ½ inches above the highest jet). Turn on the power, heater, and jets to purge any lingering air from the plumbing.

11) Balance your water and enjoy a soak in a freshly cleaned hot tub!
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