The Skipper's Blog

Ask The Skipper
Views Counter

Winterizing – Plumbing, Holding Tank and Sanitation System


Frank asked:

Hi I just received my order I am getting ready to winterize my boat. I have a 99 30′ Cruisers with inboards I used the Bilge Bath and it did a nice job, took all the odors away. Since getting this boat and after tying everything, I could not get rid of the odor in the head and sump. It was not a waste odor but it was a constant smell that no one could help with. I also noticed when pumping out, some residue stayed behind. I poured some of the Odor Free in and flushed with water, then I did it’s last pump out. The odor was gone!! The dock master, without knowing I did anything special, asked me if the holding tank was new? He said he never seen a tank that clean before on a used boat.

Thank you. Problem Solved.

Another question if you can help? How much antifreeze do you use in a 40 gallon fresh water tank and holding tank for winter storage. I keep getting different answers. Also, do you add it to the hot water heater?

For your convenience, I’ve highlighted the hyperlinks. Click on the hyperlink to get more information about the selected product.

Thanks for the feedback. We keep score and it’s nice to know that we’re still Batting 1,000.

Winterizing your fresh water system is pretty straight forward. The hot water tank can be a little tricky. The basic principal is that first you drain the system. Open all the taps on the boat, hot and cold, and let them run until the water tank is dry. When the tank is empty, turn off the water oump switch or circuit breaker to stop it from running. Pour non-toxic, plumbers antifreeze into the water tank, turn on the pump and let it run until the pink antifreeze comes through the taps. Turn off the pump and you’re done. Do not shut off the taps. Leave them open.

Be sure to only use the special non-toxic antifreeze, known as plumbers’ antifreeze. The automotive type used in car radiators should not be used as it will contaminate your plumbing system and make the drinking water poisonous. All antifreeze should be contained and disposed of in a proper disposal facility. Do not drain any of it into the water or the ground as it will cause contamination. Most boats drain their sinks overboard and you will need a friend to hold a bucket at the through hull to catch the antifreeze when it comes out.

Draining your system by pumping it through the taps will also drain some of the water out of your hot water heater, but not all. Some hot water heaters have drains, most don’t. Some are horizontal, some are vertical. If possible, drain the hot water tank separately. If it has a drain, simply open the drain and leave the hot water tap open so you don’t get a vapor lock, and it will drain into the bilge.

If there is no drain, and if it’s convenient, remove the tank from the boat, invert it to drain it and store it indoors. Do this before adding the antifreeze to the water tank. You can reinstall it in the spring and you will not have to winterize it. You may need a friend to help you with this as water weighs 10 lbs. per gallon so a tank that is full or partially full could get a little heavy. You will also need a piece of plastic or copper tubing to insert into the two ends of the hose so you can finish winterizing. It’s a good idea to clamp them onto the tubing. If you have a heat exchange connection from the motor, you will need another piece of tubing to bridge this hose, in order to winterize the engine.

If you can not remove or drain your hot water tank, you will have to compensate for the water dilution with additional plumbers antifreeze. Pour the antifreeze into the water tank as above and run the pump until you see the pink antifreeze coming out of the cold water tap. Turn off the cold water taps and continue to run the pump and keep adding antifreeze to the water tank until you see the pink antifreeze coming out of the hot water taps, then turn off the pump and open all the taps.

The antifreeze coming out of the hot water tap will initially be very light and as the strength of the antifreeze increases it will get darker. If you have a hydrometer, you can check the strength periodically until you have a sufficient antifreeze content to protect your system to the anticipated maximum temperature, otherwise keep pumping it through until it is as dark as the original in the bottle. If you can buy different strengths, use a stronger strength to compensate for the water dilution. If you can remove the hot water tank, you will probably need 1 or 2 gallons to winterize your system if you have to leave the hot water tank, you may need 4 or more gallons.

Be sure to add some of the antifreeze to the bilge and sump pumps and run them briefly to make sure that no ice forms and cracks them.

To winterize the holding tank and toilet plumbing, use the Fall Lay Up Cocktail. You can find directions and instructions in the Holding Tanks & Sanitation Systems section of the forum under How do I keep my boat from smelling in the spring?

Thanks for your question

Captain Aurora

The Skipper Recommends:
More Info
More Info
More Info