Learning how to drain the hot tub is one of those maintenance chores that sounds a lot more intimidating than it actually is, but it's something you've got to do every few months to keep your soak from getting gross. If you've noticed your water looks a bit cloudy or you're having a hard time balancing the chemicals, it's probably time to start fresh. Most experts suggest a full drain and refill every three to four months, depending on how often you're jumping in.
While it might seem easier to just keep dumping chlorine in there, water eventually reaches a point of "saturation." Think of it like a cup of coffee where you keep adding sugar; eventually, the sugar stops dissolving and just sits at the bottom. In a hot tub, we call this Total Dissolved Solids (TDS). Once that level gets too high, your chemicals won't work effectively, and your skin might start feeling itchy after a soak. So, let's get into the nitty-gritty of how to get that water out and get your spa back to its crystal-clear glory.
Before You Pull the Plug
You don't want to just walk out there and start dumping water. There are a couple of things you should do first to make sure the process is safe for your equipment and your backyard. First off, always turn off the power at the circuit breaker. You should never, ever drain a hot tub while the power is still on. If a pump turns on while there's no water, you're looking at a very expensive repair bill for a dry-run motor.
Before you actually cut the power, though, I highly recommend using a "line flush" product. This is a liquid cleaner you pour into the old water while it's still hot and the jets are running. It circulates through the internal plumbing and breaks loose all the "biofilm"—that's the nasty gunk and bacteria that builds up inside the pipes where you can't see it. Let that circulate for about twenty minutes or whatever the bottle says, and then flip the breaker. You'll be disgusted (and satisfied) by the brown foam that often comes out of the jets during this step.
Method 1: Using the Built-in Drain Valve
Most modern hot tubs come with a dedicated drain valve, usually located at the base of the cabinet. It looks a bit like the spigot you'd find on the side of your house. This is the most straightforward way to go about it, but be warned: it is slow.
To use this method, you just unscrew the cap, attach a standard garden hose, and open the valve. Make sure the other end of the hose is pointed somewhere that can handle a few hundred gallons of water. You don't want to flood your neighbor's yard or turn your own lawn into a swamp.
The downside here is gravity. Because the drain is usually right at the bottom, there isn't a lot of pressure pushing the water out. It can take several hours to empty a large tub this way. If you have the afternoon to kill and you're just hanging out around the house, this is fine. But if you're in a hurry, you'll want to look at the next option.
Method 2: The Submersible Sump Pump
If you want to know how to drain the hot tub in about twenty minutes instead of three hours, you need a submersible pump. You can pick these up at any hardware store, and they are worth every penny if you plan on staying a hot tub owner for a while.
You literally just drop the pump into the deepest part of the hot tub, attach a discharge hose, and plug it in. These things move water fast. You'll want to stay nearby, though. Once the water level gets low enough that the pump starts sucking air, you need to unplug it immediately so the motor doesn't burn out.
Even with a pump, you'll usually be left with an inch or two of water at the very bottom because of the contours of the spa seats. You can usually just mop this out with a large sponge or use a wet/dry shop vac to get those last few gallons. Honestly, a shop vac is the "secret weapon" of hot tub maintenance. It's great for getting water out of the footwell and sucking out any grit or sand that settled at the bottom.
Cleaning the Shell While It's Empty
Once the water is out, don't just start refilling it immediately. This is your golden opportunity to give the shell a good scrub. You'd be surprised how much "bath tub ring" can accumulate around the waterline.
Whatever you do, don't use household soap or dish detergent. If you do, the next time you fill the tub and turn on the jets, you'll have a foam party that would rival a Vegas nightclub. Use a dedicated spa cleaner or a simple mixture of white vinegar and water. It's acidic enough to cut through calcium deposits but gentle enough that it won't hurt the acrylic.
While you're at it, take a look at your filters. If they're looking gray or brown, give them a deep soak in a filter cleaning solution. If they're more than a year old, just toss them and put in new ones. Clean filters are the most important part of keeping your water clear, and it's a waste of time to put fresh water through a dirty filter.
Refilling the Right Way
Now that the tub is sparkling clean, it's time to fill it back up. This part seems simple, but there's a trick to it that will save you a massive headache. Put your garden hose directly into the filter housing (the hole where the filter usually sits) rather than just dropping it into the middle of the tub.
Why? It prevents airlocks. If you just fill the tub from the bottom up, air can get trapped inside the plumbing lines. When you turn the power back on, the pump will try to move water, but that pocket of air will block it, and you'll get an "FLO" or "DRY" error code on your screen. By filling through the filter pipe, you're forcing water through the pumps and plumbing first, pushing the air out as the tub fills.
Balancing the New Water
Once the water level reaches the midpoint of the skimmer or the designated fill line, you can flip the breaker back on. Don't be surprised if the heater doesn't kick in instantly; many tubs have a startup sequence that takes a few minutes.
You'll need to test the water and start adding your chemicals. Fresh tap water usually needs a bit of help with pH and alkalinity. Also, keep in mind that it's going to take a good 12 to 24 hours for the water to get up to soaking temperature, depending on the size of your heater and the temperature outside. Resist the urge to jump in while it's still 70 degrees—it's just not the same.
A Few Extra Pro Tips
- Watch the weather: Don't try to drain your hot tub if it's below freezing outside. If the water in the internal pipes freezes while the tub is empty or refilling, you can crack the manifold, which is a nightmare to fix.
- Check your local laws: Some cities have rules about where you can drain hot tub water. Because it's treated with chemicals, they might not want it going into the storm drains. Usually, the lawn is the safest bet as long as the chlorine levels aren't super high.
- The "Hose Filter": If you have hard water or high metal content in your tap water, buy a pre-filter that attaches to the end of your garden hose. It'll catch a lot of those minerals before they even enter your tub, making your chemical balancing much easier.
Knowing how to drain the hot tub properly really just comes down to having the right tools and a little bit of patience. It's a bit of work, sure, but that first soak in completely fresh, clean water makes it all worth it. Plus, your equipment will last a lot longer if it's not constantly fighting through "old" water. Happy soaking!