NOTE: please realize that most damage that occurs to hot tub spas is caused by improper winterization. The damage that can be done due to freezing is very costly to repair. Be very careful if you choose to close down your own spa. If you have any doubts, it is much better to contact a local spa professional to do this for you! Damage done to your hot tub due to improper winterization is not covered under warranty.
Start off by turning off the circuit breaker for the hot tub's electrical line, or if possible, unplug the unit. Then remove the cover and drain out the spa. This can be done by hooking a garden hose to the spa's bottom drain spout, or by actually pumping the water out with a submersible pump. Make sure you leave the bottom drain spout open when you are done.
Soak up all the remaining water from inside the spa with towels or a mop or suck it out with a shop vac. Make sure that you get all the water out, especially in the foot well. Remove the filter cartridge from the spa and make sure that all the water is out of the filter canister compartment. NOTE: Leave a large terrycloth towel in the bottom of the foot well to soak up any additional water that might get in.
Loosen or unscrew any fittings on your hot tub equipment that look like they could be loosened or unscrewed. These are usually quick disconnect fittings (plumbing unions) on either side of the heater and on either side of the pump. As you loosen each fitting, water will come out - this is what you want! Leave all fittings unscrewed. Remove any drain plugs that may be on your pump housing - this is critical! Pump housings crack easily with only a small amount of water in them. Make sure you also drain out the filter canister and the spa heater and remove any drain plugs that are there.
Blow out any residual water from the jet piping. You can use the "blowing" end of a shop vac, an air compressor or some types of leaf blowers. Get into the hot tub and put the blowing end of the hose up against each jet. Make sure that the jets are all open as wide as possible, and make sure that the topside air controls are closed. Start with the jet closest to the exhaust side of the pump and work your way around the hot tub, jet by jet. As you do this, more water will pour out of the various fittings you unscrewed at your spa equipment. After you do this to each jet, you will have removed most of the water from your entire jet system and there is little chance that any pipe or piece of equipment will still have enough water in it to freeze and cause damage. Please do not put any type of pipeline antifreeze in your hot tub, pipes or equipment. It is very difficult to get this liquid completely out of your system, and it really is not necessary if you have performed all of these winterizing procedures properly.
Get out of the hot tub and put the hard cover back on the unit. Secure the cover to the hot tub so that wind will not flip it up.
Close and secure the equipment hatch door to help prevent small animals from trying to nest inside spa cabinets over the winter. They can chew wires and cause expensive damage.
A good extra step is to place a tarp over the hard thermal cover. Placing a good tarp over the hard cover of the hot tub will keep any rain water from getting in over the winter.
To be extra sure, turn off the circuit breaker in your home breaker box (the GFCI is already off) that is for your hot tub.
Remember - If you are worried or hesitant about closing down your hot tub by yourself, we strongly suggest that you contact a local hot tub professional to perform the service for you. Most companies will guarantee their winterizing against any freeze cracks to your hot tub, pipes or equipment.