Best Submersible Pump for Draining a Hot Tub: Sizing, Safety & Steps (2026)

What Is the Best Submersible Pump for Draining a Hot Tub?

A 1/6 to 1/3 HP submersible utility pump rated roughly 1,500-3,000 GPH is the best choice for most 250-500 gallon hot tubs. Paired with a 3/4" to 1.5" garden hose or discharge fitting, it drains the tub in about 15-45 minutes. Owners in the hot tub community on Reddit land on the same type of pump again and again.

It's also the cheapest way to do the job. A basic electric submersible pump usually costs about $30-$100, which is far less than a service call. Gravity draining through the spigot often takes 1-2 hours or more, and it can't empty the tub fully if your discharge point isn't lower than the shell.

Most owners should drain and refill every 3-4 months, so a pump is a tool you'll reuse several times a year. If you want more background, we've covered how to pump to drain a hot tub and how to pick a submersible pump for your hot tub in separate guides. Here, we'll cover sizing, pump types, safety, legal discharge, the step-by-step process and what to do after draining.

How to Choose and Use a Hot Tub Drain Pump

Why and when to drain

Replace your hot tub water about every 3-4 months. Do it sooner with heavy use, cloudy or foamy water, or high total dissolved solids (the minerals and residue that build up over time). Our guide on how often to change hot tub water breaks this down by usage.

A deep clean without draining can stretch the interval a little, and we explain it in cleaning without draining. It isn't a permanent substitute, though. Eventually the water needs to go.

What size submersible pump do you need?

Most hot tubs hold 250-500 gallons. Drain time equals gallons divided by effective GPH per minute: a 400-gallon tub with a 1,200 GPH effective pump takes about 20 minutes.

Rated GPH is measured at zero lift. Every foot of head height (how high the pump has to push water) lowers flow, so check the pump's maximum head rating, which is usually 15-25 feet. The chart below shows estimated drain times at effective flow rates.

Tub size	800 GPH	1,200 GPH	2,000 GPH
250 gallons	about 19 min	about 13 min	about 8 min
400 gallons	about 30 min	about 20 min	about 12 min
500 gallons	about 38 min	about 25 min	about 15 min

Hose diameter matters too. A 3/4" garden hose is the most common fit. A 1-1/4" or 1.5" hose moves more water but needs an adapter. Use a hose long enough to reach your discharge spot, and lay it out without kinks.

Pump types compared

Each pump type has trade-offs. We've listed the main options with typical prices.

• Small utility submersible ($30-$100): Compact, cheap and a good fit for most tubs. It leaves roughly 1/8-1/4 inch of water. A hot tub drain pump like this 120V model is the kind of unit we mean.
• Sump pump ($80-$250): Powerful, but bulkier. It may not fit under the seat or in the footwell.
• Drill-powered or battery pumps ($15-$60 or more): No outlet needed, but slower and low volume.
• Non-electric siphon or water-powered options (about $20-$40): No shock risk, but slower, and they depend on water pressure or hose height.

Yes, a standard sump pump can drain a hot tub if the water has cooled below about 100°F and the pump is GFCI-protected. Many pumps tolerate roughly 100-140°F, but letting the water cool protects both the pump and you. Check the housing for chlorine and bromine resistance, since thermoplastic handles sanitizers better than unprotected metal. A pump designed for spa draining and a dedicated hot tub draining pump show the compact, flat-suction style that suits footwells. Our hot tub drain pump guide goes further on buying considerations.

What to look for:

• GFCI-protected outlet or cord
• Thermal overload protection
• Low-water cutoff or flat-suction design
• A cord of 10 feet or more
• A low residual water level

You don't need a check valve for draining. Owners in this hot tub owners group thread often share what's worked for them, and it's a useful reality check before you buy.

Safety

Water and electricity demand respect. Shut off power at the breaker before you start. Never run a pump from an ungrounded extension cord. Keep plugs dry and off wet ground, and don't stand in water while handling the pump. Our hot tub safety rules and hot tub electrical requirements cover this in more depth.

Step-by-step: draining with a submersible pump

Gather your gear first. Our cleaning supplies checklist helps. Then follow these steps.

1. Turn off the breaker.
2. Remove and rinse the filters.
3. Lower the pump into the footwell or lowest point and attach the hose.
4. Run the hose to a legal discharge location.
5. Plug into a GFCI outlet and start the pump.
6. Monitor it so the pump doesn't run dry.
7. Finish the last inch with a wet/dry shop vac or sponge.

Where to discharge

Let the sanitizer dissipate before you pump, or neutralize it with a dechlorinating agent such as sodium thiosulfate or sodium sulfite. Our post on chlorine neutralizer for hot tubs explains the process. Aim for a pH of 6.5-8 and a near-zero sanitizer residual.

In the US and Canada, many municipalities allow discharge to a sanitary sewer cleanout or onto a lawn. Storm drains, streams and neighbors' yards are off limits. Check your local bylaws before you start.

Drain without a pump

You can use the drain spigot with a garden hose, siphon the water, or try a non-electric water-powered option. It's slower and often leaves more water behind, so expect extra sponge and shop vac work.

After the drain

Wipe the shell with a non-abrasive spa cleaner, and flush your hot tub lines. Rinse or replace the filters, then refill using a hose filter. Next, balance the water after refilling: alkalinity first, then pH and sanitizer. If the fresh water turns hazy, our cloudy spa water guide can help.

Once the water's balanced, the TubTabs weekly tablet routine ($119.99) keeps things simple. The Hot Tub Complete Care Kit, with 15 TubTabs and 25 BroTabs ($159.99), lasts about 3-4 months and replaces a shelf of separate chemicals. If you're building your toolkit, see these affordable hot tub accessories too.

Drain Smarter and Keep the Refill Simple

A 1/6-1/3 HP submersible pump, a GFCI outlet and a legal discharge spot turn draining into a 15-45 minute job. Neutralize the sanitizer, protect the shell and filters, and finish the last inch with a shop vac. A pump built for draining spas is a small investment that pays off every season.

After refilling, a once-weekly routine keeps the water clear. We recommend the Hot Tub Complete Care Kit ($159.99), a Canadian-made bundle of TubTabs and BroTabs, delivered to your door. Then use a hot tub maintenance checklist to log your next drain date, 3-4 months out.

Stop juggling multiple chemicals. Try TubTabs.

Frequently Asked Questions About Draining a Hot Tub with a Pump

What is the best submersible pump to drain a hot tub?

The best choice for most owners is a 1/6 to 1/3 HP utility submersible pump rated 1,500-3,000 GPH, with a 3/4" to 1.5" hose connection, thermal overload protection and a GFCI-protected cord. It typically costs $30-$100 and drains a 250-500 gallon tub in about 15-45 minutes.

What size submersible pump do I need for a hot tub?

Most hot tubs hold 250-500 gallons, so a pump delivering at least 1,000 effective GPH works well. Divide your tub's gallons by GPH per minute to estimate time: 400 gallons at 1,200 GPH takes about 20 minutes. Account for lift height, because flow drops as the hose rises.

How to drain a hot tub with a submersible pump?

Turn off the breaker, remove the filters, place the pump at the lowest point, and attach a hose leading to a legal discharge spot. Plug into a GFCI outlet and run until the water is nearly gone. Unplug, then remove the last inch with a shop vac or sponge.

Is there a sump pump I can use for a hot tub?

Yes. A standard sump pump can empty a hot tub if the water has cooled below about 100°F, the housing resists chlorine and bromine, and it's plugged into a GFCI outlet. Sump pumps are bulkier and may leave more residual water than a flat-suction utility pump, so check fit first.