Yes, but also do the potable water system, the head, the air conditioner's raw water system, any raw/fresh water wash down system and the generator. David
SANITATION SYSTEM
Holding tank should be pumped out and THOROUGHLY rinsed out before winterizing the toilet. If the toilet uses sea water, just flushing antifreeze through the bowl will not protect the intake line, the toilet pump or the bowl...it'll only go out the discharge to the tank. Disconnect the flush water inlet hose from the thru-hull (might be a good idea to close the seacock first if the boat is still in the water) and stick it into a jug of non-toxic potable antifreeze. Flush the toilet to run it through the entire system. If the toilet uses onboard pressurized fresh water, winterizing the fresh water system also winterizes the toilet...winterize the tank by flushing the antifreeze down the toilet. Follow mfr's instructions--found in the owners manual-to winterize any treatment device (Lectra/San, ElectroSan, PuraSan).
FRESH WATER SYSTEM
1. Drain the water tanks completely (just turn on all the faucets).
2. Drain water heater. Most have a drain petcock; follow manufacturer’s instructions to find it and use it. Remove both the inlet and outlet hoses, and if necessary use a shop vac to be sure of getting all the water out of it.
3.Do NOT put antifreeze in the water heater. Connect water heater inlet and outlet hoses together to bypass it. Bypass kits for this purpose are available from boat stores and RV supply stores.
4. Add non-toxic antifreeze ("the pink stuff") and pump that through the system until all outlets--hot and cold in the galley, head, shower, and any deck wash--run only antifreeze. Leave all the faucets open to make sure there is no pressure in the system.
As an alternative to antifreeze, some owners prefer to use an air compressor to blow all the water out of the plumbing. This does require disconnecting some fittings in low places where water can pool.
(All this is in my book, btw..the title in my signature is the link to it)
Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein