Expert winter maintenance tips from Xylem for Jabsco pumps and marine toilets

Before you put the boat away for winter, make sure your pumps and toilet are ready too. Follow these practical winterization tips from Xylem’s Jabsco brand to help protect your onboard systems and make spring startup easier.

General principles: The five rules that apply to every pump and toilet

No matter which pump or toilet you’re winterizing, the same core principles apply. Following them can help protect your system from freeze damage and make spring commissioning smoother.

• Use non-toxic propylene glycol only: Always winterize with non-toxic propylene glycol antifreeze (the familiar pink fluid). Never use automotive ethylene glycol antifreeze. It is toxic, it has no place in a marine sanitation or raw-water system, and it must never be discharged overboard or into a holding tank. Dispose of any antifreeze in accordance with local regulations.
• Close the seacock and cut the power first: Before you touch a hose, close the through-hull seacock and isolate power to the pump. This is the single most important safety step.
• Winterize both the inlet and the discharge side: A common failure is to push antifreeze only through the pump and out the discharge, leaving the inlet hose from the seacock full of water. That trapped water freezes and splits the hose or the pump inlet. You still have to winterize the hose between the pump and the seacock.
• Run enough antifreeze to fill the whole line: Keep pumping until you see pink at every discharge point, then run a little more. If you have, for example, 4 ft. (1.2 m) of inlet hose and 8 to 9 ft. (2.4 to 2.7 m) of discharge hose, make sure the antifreeze travels the full length of the discharge into the holding tank or overboard. A gallon or two (3.8 to 7.6 liters) is typical; some systems take more.
• Remember recommissioning in the spring: Before you re-energize any pump, open the seacock first. Running a dry pump against a closed seacock can damage the impeller or diaphragm. This is the most easily forgotten step after a long winter.

Winterizing a Xylem Jabsco washdown pump

Washdown pumps are often tucked into tight quarters, but the job takes only about 10 to 15 minutes.

What you need: A nut driver or flat-head screwdriver, about 3 ft. (0.9 m) of hose with a Par-Max quick-disconnect fitting on the end, and a gallon (3.8 liters) of pink propylene glycol antifreeze.

The steps:

1. Cut the power to the pump and close the seacock.
2. Use the screwdriver to release the quick-disconnect clip on the pump’s port fitting and remove the fitting.
3. Fit your short length of hose with the Par-Max fitting onto the pump and run the other end into your antifreeze.
4. Restore power to the pump, then go out to the washdown nozzle and squeeze the trigger. You will see clear water first, then pink antifreeze. Once it runs pink, shut the pump down. It took Jabsco’s team about seven-eighths of a gallon to fill the system.
5. Do not forget the inlet hose from the seacock to the pump. Either pour propylene glycol into that hose to displace the water or disconnect the hose at the seacock and drop it into the antifreeze jug so the pump draws antifreeze up through the inlet hose as well.

Spring reminder: Open the seacock before you re-energize the pump.

Winterizing a Xylem Jabsco circulation pump

Circulation pumps (such as Xylem’s Jabsco Cyclone series) are a little quirky because they are not self-priming, so you cannot simply drop a hose into a jug and let the pump suck. Instead, you gravity-feed the antifreeze in while the pump runs.

What you need: A nut driver or flat-head screwdriver, a funnel, and a gallon (3.8 liters) of antifreeze.

The steps:

1. Close the seacock. 
2. Disconnect the feed hose from the seacock.
3. Lift the hose and fit the funnel into the top of it.
4. With the pump running, pour propylene glycol down the funnel so it gravity-feeds through the pump and on through the system it serves.
5. Let it run long enough to push antifreeze through the entire circuit.

Because these pumps are not self-priming, the funnel-and-gravity method is the reliable way to fill the pump head and the downstream lines. Expect about 15 to 20 minutes.

Winterizing a Xylem Jabsco flexible-impeller pumps

Flexible-impeller bilge pumps are used where a centrifugal pump will not work, such as inside a dry gear locker where water might occasionally collect. Because they are self-priming, they can draw fluid up and out of a compartment, which makes winterizing them straightforward.

What you need: A nut driver or flat-head screwdriver, one or two gallons (3.8 to 7.6 liters) of pink antifreeze.

The steps:

1. Take the pump’s inlet hose and place it directly into your container of antifreeze.
2. Switch the pump on. You will hear a sound change as it moves from sucking air to pulling fluid.
3. Let it run long enough to push antifreeze through both the inlet side and the discharge side. One to two gallons (3.8 to 7.6 liters) is usually enough to fill the whole system.

This is one of the quickest winterization jobs: roughly 15 to 20 minutes.

Winterizing a Xylem Jabsco raw-water marine toilet

Xylem’s Jabsco raw-water marine toilets are fitted with a diaphragm pump that brings flush water into the bowl. That pump, plus the full inlet and discharge path, must be winterized.

What you need: A nut driver or flat-head screwdriver, a Par-Max quick-disconnect fitting with a short length of hose, and a couple of gallons (a few liters) of antifreeze.

The steps:

1. Locate the rinse/flush pump. It may be in the bilge or behind a console or cabinet.
2. With the seacock closed, use the screwdriver to release the quick-disconnect clip on the pump’s port fitting and remove the port fitting. Watch for residual water.
3. Fit your alternative Par-Max fitting with the short hose onto the pump, replace the clip, and run the hose into your jug of antifreeze.
4. Go to the head and run the toilet. You will see residual water first, then pink antifreeze entering the bowl. Hold the flush until antifreeze has travelled the full length of the discharge hose into the holding tank or overboard discharge.
5. Winterize the inlet hose between the diaphragm pump and the seacock. Disconnect that hose at the pump inlet, pour propylene glycol down into it, and reattach it. This protects the inlet side, which is the part most commonly missed.

Allow a couple of gallons (a few liters), sometimes a little more, to ensure the antifreeze reaches all the way through the discharge. If you have 4 ft. (1.2 m) of inlet hose and 8 to 9 ft. (2.4 to 2.7 m) of discharge run, the extra antifreeze is what gets you fully protected.

Before you start: Pump out the holding tank and give the system a thorough fresh-water flush so you begin spring with a clean slate. Frozen waste left in a tank is unpleasant and can damage the tank.

Winterizing the macerator pump and sanitation discharge

A macerator pump handles the discharge side of the sanitation system, grinding waste into a fine slurry before sending it to the holding tank or overboard. It is the natural companion to the toilet winterization above and should not be overlooked.

The steps:

1. Ensure antifreeze has been flushed through the toilet and into the holding tank.
2. Run the macerator pump for about 30 seconds to draw antifreeze from the holding tank, through the macerator, and out the overboard discharge.
3. Have someone watch the overboard discharge. When they see the pink antifreeze being pumped out, stop the pump and close the through-hull.

Macerator pumps should never be run dry for extended periods, as this can damage the impeller. A short 30-second run with antifreeze is enough to protect it through the winter.

Notes on holding tanks and seacocks

• Pump out and flush the holding tank first: Start winterization with an empty, clean tank. Pour an approved toilet cleaner into the bowl, let it sit, then flush and rinse before introducing antifreeze.
• Leave seacocks closed for the winter: Once the system is winterized, leave the intake and discharge seacocks in the closed position. Reopen them in the spring before re-energizing any pump.
• Winterize the tank and seacocks independently: The holding tank, seacocks, and any treatment system should each be winterized following the manufacturer’s instructions. Antifreeze poured only into the bowl protects the discharge side but can leave the intake side of the pump exposed to freezing.

Common winterization mistakes to avoid

• Automotive (ethylene glycol) antifreeze: Automotive antifreeze is toxic to humans, pets, and aquatic life, and it has no place in a marine sanitation or raw-water system. It must never be discharged overboard or into a holding tank. Always use non-toxic marine/RV propylene glycol (the pink fluid) instead.
• Alcohol-based antifreeze: Some cheap "RV antifreeze" products are blended with ethyl alcohol. Alcohol swells and degrades rubber parts, including pump diaphragms, impellers, and toilet joker valves. If the label says "combustible," walk away. A true propylene glycol product is not flammable.
• Diluting pre-mixed antifreeze: Most -50°F (-40°C) and -60°F (-16°C) marine antifreeze is already pre-diluted and designed to be used full strength. Adding water raises the freeze point and reduces protection. Use it straight from the jug.
• Pumping a pump dry and calling it done: You cannot simply run a pump until it stops moving water and assume the system is winterized. Water stays trapped in low spots in both the suction and discharge lines and inside the pump housing, where it can freeze and crack the housing. Antifreeze must be circulated through to displace that residual water.
• Stopping as soon as you see pink: The first pink that appears is antifreeze mixed with the water already in the system. It has not fully displaced that water yet. Keep running the pump or flushing the toilet until you are confident the entire line, all the way to the holding tank or overboard discharge, is filled with antifreeze.
• Bleach and harsh household cleaners: If you clean the toilet or holding tank before winterizing, avoid bleach, drain cleaners, and harsh chemical deodorizers. These degrade rubber seals and joker valves, sometimes within a single season. Use a mild biodegradable detergent or a cleaner approved by the toilet manufacturer, then rinse thoroughly before introducing antifreeze.
•  Petroleum-based oils on rubber parts: Some boaters flush petroleum or vegetable oils through the toilet as part of winter layup to keep seals supple. Petroleum-based oils damage rubber components, and independent testing has shown that vegetable oils degrade neoprene joker valves and seals. For lubrication during winterization, follow the manufacturer's guidance, which calls for silicone lubricants on specified components only.

Quick-reference checklist

• Close the seacock and cut power to every pump
• Use non-toxic pink propylene glycol, never automotive antifreeze
• Push antifreeze through until pink appears at every discharge
• Winterize the inlet hose between the pump and the seacock, not just the discharge
• Run enough antifreeze, a gallon or two (3.8 to 7.6 liters); more for long discharge runs
• For circulation pumps, gravity-feed with a funnel since they are not self-priming
• For toilets, flush antifreeze all the way to the holding tank or overboard
• Run the macerator briefly to pull antifreeze through the discharge
• Pump out and flush the holding tank first
• Leave seacocks closed for winter; reopen before re-energizing pumps in spring