How do I drain and clean a hot tub?
Turn the power off at the breaker, take out the filters, and run a garden hose from the drain valve to a spot where chlorine-free water can go. Scrub the shell with a non-abrasive spa cleaner, deep-clean the filter, then refill with tap water and restart. Cal Spas says to do this every four to six months; check your own manual.
Free to ask. Local shops send quotes, and you pay only when you book one.
By Kasra Taheri, Founder, LoclisPublished
Researched and drafted with AI, then checked claim by claim against the sources listed below before it was published. Prices and rules change; the dates beside each source say when it was last checked.
Step by step
Read when to stop and call a pro, further down this page, before you start.
Step 1: Turn off the power
Switch the spa off at its breaker before you start, and take out the filters.[1]
Step 2: Let the sanitizer fade
Stop adding sanitizer several days ahead and test the water, because only dechlorinated water should go to a storm drain.[2]
Step 3: Find the drain
On a Cal Spas model, pull the knob out of the cabinet to reach the drain, then check that the valve is closed before you remove the cap.[1]
Step 5: Open the valve and drain
Open the valve and leave it until the spa is completely empty.[1]
Step 6: Clean the shell
Wipe the empty shell with a mild detergent or a non-abrasive cleaner made for spas, then rinse.[1]
Step 7: Deep-clean the filter
Soak the filter in a bucket of filter cleaner for at least 24 hours, then spray between the pleats with a hose.[1]
Step 8: Close the drain
Close the valve, take off the hose and put the cap back on.[1]
Step 9: Refill with tap water
Fill through the filter well to about six inches from the top, using a hose pre-filter if you fill from a well.[1]
Step 10: Restart and test
Reinstall the filter without over-tightening, turn the power back on at the breaker, then test the water and adjust the chemicals.[1]
You drain a hot tub in about an hour of work plus the time the water takes to run out, and the sequence is the same on most portable spas: power off, filters out, drain with a hose, clean the empty shell, clean the filter, refill with tap water, power on, balance the chemicals. This guide follows the Cal Spas owner's manual; other brands differ in where the drain is and how often they want it done, so keep your own manual open.
How often to drain
Cal Spas' manual says: "Your spa should be drained every four to six months for cleaning and maintenance and refilled with fresh tap water."[1] A tub used daily by several people sits at the short end of that range; one used on weekends can go longer.
Before you drain
Switch the power off at the breaker and take out the filters.[1] The manual's own order is: "Before you begin turn the power off to the spa at the breaker and remove your filters."[1] Nothing should have power while the water is out.
Plan where the water goes. Hot tub water carries sanitizer, and Prince William County says the chlorine, bromine, algaecides, cleaning chemicals, and lack of dissolved oxygen in pool water can kill fish and other aquatic life in streams.[2] The county's ordinance allows only "de-chlorinated, pH neutral, chemical-free, clean water" to be "slowly discharged to the storm drain system."[2] Its advice is to use removal agents or "allow untreated water to sit for approximately 10 days to allow the chlorine or bromine to dissipate," then test for any chlorine or bromine and check that the pH is neutral.[2] Stafford County lists chlorinated pool water among its illicit discharges and dechlorinated swimming pool discharges among the allowable ones.[3] These are county rules from two Virginia counties, not a statewide rule, so ask your own locality.
In practice: stop adding sanitizer a few days ahead, test the water with a strip, and run the hose onto a vegetated part of your yard, away from the neighbor's property and the street.
Drain it
On a Cal Spas model, "Pull the knob out of the cabinet."[1] The drain is behind it. "Make sure the valve is in the closed position, then unscrew and remove the cap."[1] Then: "Attach a garden hose to the hose-bib fixture. Place the other end of the garden hose where you would like the water to drain too."[1]
Open the valve. A few hundred gallons takes a while, and the last inch or two will not drain by gravity. A wet/dry vacuum or a sponge handles that. When the tub is empty, close the valve, take off the hose and put the cap back on.[1]
Clean the shell
An empty tub is the time to clean the shell. The manual says: "Each time you drain the spa, before you refill it you should clean your spa shell with an all purpose cleaner and apply a coat of surface protectant."[1] The cleaner should be a "mild detergent, non-abrasive cleaner specifically formulated to clean the spa without damaging acrylic finish."[1] Skip scouring pads, and do not use household bleach.[1] Pay attention to the waterline and to the jets, seats and footwell, where film collects. Rinse everything well, because leftover detergent foams when the jets start.
While you are in there, look at the suction fittings. The manual says they become brittle after constant exposure to sanitizers, so "inspect suction fittings for any cracks or damage."[1] A cracked fitting is a repair, not a cleaning job.
Clean the filter
Do it while the tub is empty. The manual's method is to soak the filter in a bucket with filter cleaner, using "on average most manufactures recommend 8 ounces of chemical cleaner, verify the amount used on your chemical instructions." It then says "Soak the filter for a minimum of 24hrs" and "Spray the filter with a water hose, with careful attention between filter pleats."[1] A spare filter lets you swap one in while the other soaks. Reinstall the filter and "do not over tighten the filter," because the plastic threads inside the canister can strip.[1] Its warning is to "never run the spa without a filter."[1]
Refill and restart
Fill with "regular tap water about six inches from the top."[1] The manual is blunt about one thing: "Never fill with soft water."[1] Well water is allowed only with a hose pre-filter and a test for total dissolved solids and metals.[1] Put the hose into the filter well to keep air from being trapped in the pump.
When the spa is filled to the correct level, turn on the power at the GFCI breaker.[1] Let the pumps prime, put the cover on while it heats, and test the water. After you balance it, add a sanitizer designed for spas. The manual says: "Don't use household bleach (liquid sodium hyperchlorite)."[1]
Stop and call a pro if
- The GFCI trips or will not reset. The manual says: "If the GFCI does not reset, unplug the spa" and have it looked at.[1] A tripping GFCI is a wiring or equipment fault, not something to reset repeatedly.
- You find anything wrong with the wiring, a damaged cord or a burnt smell at the disconnect. In Virginia, "no individual shall engage in, or offer to engage in, work as a tradesman as defined in § 54.1-1128 unless he has been licensed under the provisions of this article."[4]
- A suction fitting is cracked or the shell has a crack, blister or leak.
- The tub will not drain, or water keeps coming back to the drain valve after it is closed.
Getting help in Virginia
If it is easier to hand the job off, read whether a hot tub maintenance service is worth it and what hot tub service costs in Virginia. Browse pool and spa answers or pool and spa services on Loclis.
When you are ready, describe your hot tub once and local pros quote it.
Common questions
- How often should I drain a hot tub?
- Cal Spas' manual says: "Your spa should be drained every four to six months for cleaning and maintenance and refilled with fresh tap water."[^calspas] Other makers give different intervals, so check your manual, and drain sooner if the water stays cloudy or smells after you have balanced it.
- Where can I drain hot tub water?
- Prince William County's stormwater page says that, by county ordinance, "only de-chlorinated, pH neutral, chemical-free, clean water may be slowly discharged to the storm drain system."[^pwc] Stafford County's brochure lists chlorinated pool water as an illicit discharge and dechlorinated swimming pool discharges as allowable.[^stafford] Rules differ by locality, so ask your county or town before you drain toward the street.
- Can I use bleach to clean my hot tub?
- Not for sanitizing. Cal Spas' manual lists "Don't use household bleach (liquid sodium hyperchlorite)."[^calspas] For the empty shell, use a mild detergent or a non-abrasive cleaner made for spas, and rinse well.
- Can I fill my hot tub with softened water?
- No. The Cal Spas manual says "Never fill with soft water."[^calspas] It adds that you may fill with well water only if the preconditions in the manual are followed, which include a hose pre-filter and a test for total dissolved solids and metals.
- Do I have to clean the filter every time I drain?
- It is a good moment to do it. The manual recommends a deep clean of the filter at least once a month or every two weeks depending on use, and says never to run the spa without a filter.[^calspas]
Sources
- [1] Patio and Patio Plus Owner's Manual 2025, Cal Spas. Checked October 27, 2026.
- [2] Stormwater Pollution Reduction, Prince William County, Department of Environmental Services. Checked October 27, 2026.
- [3] Illicit Discharge, Detection, & Elimination Program, Stafford County, Virginia. Checked October 27, 2026.
- [4] Va. Code § 54.1-1129, Tradesman license required, Code of Virginia, Virginia General Assembly. Checked October 27, 2026.
Want a pro to handle it?
Describe the job once. Licensed local businesses send quotes, and you pay only when you book one.
Get a quote from a local pro