RV Winterization Checklist: 8 Easy-to-Miss Places That Can Freeze

A proper RV winterization checklist includes more than the kitchen faucet, bathroom sink and shower. Modern RVs can have exterior spray ports, pump strainers, water filters, tank-flush connections and appliance supply lines that hold water even after the main plumbing appears empty.

That is why an RV can show pink antifreeze at every indoor faucet and still suffer freeze damage somewhere else.

At Basecamp RV, we treat winterization as a system-wide process. The goal is to remove trapped water, protect the remaining plumbing and account for every water-using option installed on that specific coach.

Why a basic RV winterization checklist can miss components

Opening the low-point drains does not guarantee that every section of plumbing will empty. Check valves, uphill hose runs, filter housings and small appliance valves can retain water.

Compressed air can clear many lines, but it does not automatically protect drain traps or every isolated accessory. Pumping RV antifreeze through the freshwater system protects many components, but it may bypass separate lines such as a black-tank flush connection.

The strongest process follows the RV manufacturer’s instructions and accounts for the actual floor plan and installed equipment. Use only non-toxic RV or marine plumbing antifreeze. Automotive antifreeze does not belong in an RV freshwater system.

1. The water heater and its bypass valves

The water heater must be turned off, allowed to cool and depressurized before draining. The drain plug or anode rod then has to be removed according to the heater manufacturer’s procedure.

Draining the tank is only part of the job. The bypass valves must be placed in the correct winterization position before antifreeze is pumped through the coach. Otherwise, several gallons of antifreeze may fill the heater instead of protecting the plumbing lines.

Tankless heaters and combination heating systems can have different drain points and winterization procedures. Do not assume the three-valve bypass arrangement used with a conventional tank heater applies to every system.

2. Exterior showers, spray ports and outside kitchens

Exterior fixtures are easy to forget because they sit behind compartment doors. They are also exposed to colder temperatures than many interior fixtures.

Check the coach for:

• Hot-and-cold exterior shower valves

• Quick-connect spray ports

• Outside kitchen faucets

• Outdoor refrigerator ice-maker or water connections

• Utility-compartment washdown faucets

Connect any removable spray hose required to open the fitting, then operate the hot and cold sides according to the coach instructions. A capped quick-connect can retain water behind its internal valve even when nearby plumbing has been cleared.

3. The city-water inlet and check valve

The city-water connection contains a check valve that prevents water from flowing back out of the coach. Water can remain trapped near that valve if the inlet is not included in the winterization procedure.

Do not blindly press the check-valve stem because a video says to do it. On some systems, depressing the valve while the plumbing is pressurized can dislodge or damage the seal. Follow the coach manufacturer’s procedure for relieving pressure and clearing the inlet.

If compressed air is used, connect it through a regulated blowout fitting and stay within the pressure limit specified by the RV manufacturer. There is no single air-pressure number that should be applied to every coach or every auxiliary system.

4. Low-point drains and water-management valves

Most RVs have separate hot and cold low-point drains, but their location is not always obvious. A water-management panel can also contain several valve positions for city water, tank filling, sanitizing and winterizing.

The valve diagram on the panel or in the owner’s manual matters. One incorrect valve position can isolate a section of plumbing or send antifreeze into the freshwater tank instead of through the fixtures.

After draining, confirm that every low-point cap or valve is returned to the position required for the next winterization stage. Leaving one open while drawing antifreeze can pull air into the system and prevent the pump from priming.

5. The water-pump strainer and inlet hose

Many RV water pumps have a clear plastic strainer bowl on the inlet side. That small bowl can hold enough water to crack when frozen.

Winnebago’s current owner documentation specifically calls for emptying the pump-strainer bowl when using a blowout winterization procedure. The same concern applies to many coaches using a similar pump and strainer arrangement.

Inspect the bowl, screen and seal while it is accessible. Reinstall it correctly before using the pump to draw antifreeze. An improperly seated bowl or O-ring can cause an air leak that makes the pump run without pulling fluid.

6. Water-filter housings

Whole-coach filter canisters, under-sink filters and refrigerator filters can trap water. A filter housing may look empty while water remains in the bottom or inside the cartridge.

Follow the filter manufacturer’s storage instructions. Depending on the system, the cartridge may need to be removed and the housing emptied, cleaned or bypassed. Do not assume RV antifreeze should be pumped through every drinking-water filter.

Record which cartridges were removed so they are not forgotten during spring startup.

7. Toilets, P-traps and water-fed appliances

Operate the toilet valve until its supply is protected using the method specified for the coach. Then protect the drain traps under each sink and shower. Clearing the freshwater lines does not remove water from a P-trap.

Inspect the RV for additional water-fed equipment:

• Refrigerator ice makers and water dispensers

• Clothes washers

• Dishwashers

• Onboard drinking-water systems

• Additional half-bath fixtures

These accessories often have their own pumps, solenoids, filters or drain cycles. Run the appliance manufacturer’s winterization procedure rather than assuming antifreeze at the nearest faucet protects the appliance.

8. The black-tank flush connection

The black-tank flush is a separate water line on many RVs. Pumping antifreeze through the freshwater fixtures normally does not protect it.

Grand Design owner manuals, for example, instruct owners to blow out the black-tank flush line from its exterior connection. That instruction applies to those specified systems and should not be treated as a universal pressure setting for every RV.

Use the procedure and pressure limit for the actual coach. The tank-flush line can include a check valve, vacuum breaker and piping routed through interior spaces, all of which need to be considered.

A final check before the RV goes into storage

Before closing the compartments, verify that:

• The water heater is drained and configured correctly

• Every interior and exterior fixture was included

• The pump strainer and filter housings are protected

• Appliance-specific procedures are complete

• Drain traps contain the correct RV plumbing antifreeze

• Auxiliary lines such as the tank flush were handled separately

• The water pump and water heater switches are off

• Removed plugs, caps and filter cartridges are labeled for spring startup

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Take a few photos of the water-management panel, bypass-valve positions and removed components. Those photos make de-winterization easier and provide a record of what was completed.

Winterization failures usually happen in the component that was not included in the plan. A coach-specific checklist is more reliable than counting how many faucets turned pink.

Basecamp RV provides mobile RV winterization using a staged air-and-antifreeze process. Call 801-609-8522 to schedule service before freezing temperatures arrive.