An RV that freezes does not fail evenly and it does not announce itself. Jayco, KZ RV and Venture all put the same number on the risk, 32 degrees Fahrenheit, and the damage happens in the parts that hold water: the pump head, a filter housing, the toilet's supply valve, the ice maker solenoid and the water heater tank. What matters now is the order you bring it back in, and the pump is what tells you whether something let go.
Last reviewed: Sep 24, 2026.
This is the one step that has to happen while the system is still frozen, and it is the difference between finding a leak and being sprayed by one.
Switch the pump off at its own switch, not at the breaker alone, and open a tap, the lowest one if you can reach it. Ice expands, and a fitting that has split can sit there holding with no pressure behind it. The moment the ice melts and the pump is live, that fitting has a working pump behind it and a room full of your things in front of it. Leaving a tap open gives the water somewhere to go.
If the coach is on shore power, treat water near a fitting as a live risk. The converter, the outlets and the water heater's electrical side are all in the same compartments as plumbing. If a leak appears anywhere near them, kill the breaker for that area before you go poking at it.
Do not try to drain a frozen system. Low-point drains, dump valves and the water heater's drain plug all need water to move through them. Opened while the contents are solid, they break rather than drain.
No torch, no heat gun, no propane torch attachment, and no boiling water poured over a fitting. An RV's water lines run through foam, plastic and wood, and every one of those is a material that a directed flame will damage faster than it thaws the pipe. A fitting that has already cracked will also fail suddenly as it heats, which is the moment you least want to be holding it.
The safe shape is indirect heat: run the furnace, put a space heater in the living space with the cabinet doors open so warm air reaches the plumbing, and leave it. A hair dryer on a low setting, held well back and kept moving, is the most direct anything should get.
Watch the places where water leaves the system, because those thaw last and they are where you will see the first sign of trouble: the low-point drains, the toilet base, the cabinet under the sink, and the wet bay. A stain that appears during the thaw is doing you a favour by pointing at its own fitting.
A water system holds pressure. When everything is closed and the pump has run, the pump stops and stays stopped, because there is nowhere for the water to go. A leak gives it somewhere to go, so the pump starts again. That is why the test is worth more than a visual inspection: with every fixture shut off, a pump that runs or cycles is reporting a loss of pressure, and it reports it before water reaches a floor you can see.
Look at the pump and its strainer before you switch it on. Both hold water by design, and the pump maker's own troubleshooting list names the housing for cracks. A housing that has already split will spray the moment the pump runs, so the check costs a few seconds and it is the one failure the test itself can make worse.
Run the test deliberately. Close every tap and valve, turn the pump on, let it build pressure and stop, then stand still and listen for two or three minutes. A pump that runs once and settles is doing its job. A pump that pulses every half minute is losing water somewhere.
Small leaks are the ones that hide, because a cracked housing under a cabinet can lose water slowly enough that it evaporates or runs into the belly pan rather than onto a floor. That is why the pump test comes before the visual pass, and why the visual pass should include the underside of the pump itself, under the sink, and the floor of the wet bay with a torch.
Freeze damage follows water, not cold. Ice does its work where water sits and has nowhere to expand into, which is why the list is short and specific rather than a tour of the whole system.
The pump maker is direct about the stakes. SHURflo's manual for its RV pumps states: If water is allowed to freeze in the system, serious damage to the plumbing and pump may occur. Failures of this type will void the warranty. FloJet's wording is the same in fewer words: Allowing water to freeze in the system may result in damage to the pump and plumbing system.
SHURflo and FloJet publish the same protective step, and it is the one to do before the next freeze rather than after this one. SHURflo's order: drain the water tank, open every faucet including the lowest drain, let the pump purge the lines, then turn the pump off, disconnect the plumbing at the pump's inlet and outlet ports, and turn the pump on again briefly so the head empties into a pan. FloJet's version is to remove the quick connect fittings from the pump and run it to expel the water from the head.
SHURflo's troubleshooting list names the two failures to look for after a freeze: the pump housing for cracks, or loose drive assembly screws, and a seized or locked diaphragm assembly, which its own note attributes to frozen water. A pump that runs loudly, will not build pressure or leaks from the body has one of those two.
A filter housing is a bowl of standing water bolted into the system, and standing water is what breaks housings. An inline filter is also the one part of a water system that is not winterised in place, which makes the step the same after a freeze as before one: take the cartridge out, keep it the way its own label says, and leave the housing empty.
For a system that has already frozen, treat the housing as a suspect and look at it with the pump test running rather than by eye. A hairline split in a plastic bowl is easy to miss and easy to find once there is pressure in it.
A toilet holds water in its valve and in the short supply line behind it, and it is one of the few places where a frozen system has to be handled differently rather than just thawed. Thetford's owner manual for its RV toilets gives two instructions that matter after a freeze:
Thetford's winterising method for the toilet is to turn the water supply off, drain the bowl, disconnect the supply line at the water valve and drain that line completely. After a freeze, the same connection is where a weep will show: check the fitting at the valve with the pump pressurised, and if it leaks at the valve body rather than at the fitting, the valve is the part.
Norcold's owner manual states: Do not operate the ice maker when the ambient air temperature is 0 degrees F. or lower. Damage to the water solenoid valve and the water supply line can occur. It also states plainly what the fridge's own protection does not cover: The water line heater does not protect the water supply line from the vehicle shut off valve to the solenoid valve on the back of the refrigerator.
Dometic's refrigerator manual describes the same arrangement from the other side: an ice maker model carries a heater tape wrapped around the water solenoid valve and the outlet tube, switched on automatically below 32 degrees. Both makers give the same storage step, and the difference between them is why it matters: shut the supply valve off, then disconnect the water lines from the inlet and outlet sides of the solenoid valve and drain them.
So the run that freezes is the one behind the fridge between the shut-off valve and the solenoid, and the failure is a cracked solenoid valve or a split line rather than anything visible in the freezer.
A single-handle faucet and a shower mixer both hold a cartridge of standing water, and a cartridge that has frozen can weep from the base of the tap rather than from a joint. The check is a check rather than a citation: with the system pressurised and the tap closed, dry the base of each tap with a cloth and watch it. A tap that beads water while it is closed has a cartridge or a seat problem, and the part is cheap.
Three things get said about PEX and freezing: that RV plumbing is PEX, that PEX survives a freeze, and that the fittings are what crack. The Plastics Pipe Institute supports the first two, says nothing at all about the third, and qualifies the second in ways that matter, which is why it changes what you check.
The Plastics Pipe Institute's technical report on freeze break resistance states the supported half clearly: The inherent flexibility of crosslinked polyethylene also results in excellent freeze break resistance properties. This means that if water- or fluid-filled PEX pipe or tubing freezes, the elasticity of the material typically allows it to expand without cracking or splitting, and then to return to its original diameter upon thawing.
The same report then says three things that the popular version leaves out:
The practical version for a reader whose coach has frozen: the tube is the part most likely to have survived, the parts that hold water are the ones to inspect, and a system that came through one freeze is not a system that tolerates freezing. Nothing here should be read as permission to skip winterising.
Suburban's own operation and maintenance guide is unambiguous: If RV is to be stored during winter months, the water heater must be drained to prevent damage from freezing. Its freeze warning repeats it, and it publishes the drain order, which is the part that gets done wrong. Turn the electrical power off at the switch or the breaker, shut off the gas supply, turn the water pump off, open both the hot and cold faucets, then remove the anode rod from the front of the heater with a 1-1/16 inch socket, and finish by draining the rest of the system the way the coach maker describes.
On the Suburban tank heaters covered by that manual, the anode rod is the drain, and it is also a part worth looking at while it is out: a rod that has been consumed is the cheapest thing to replace before it disappears and starts eating the tank instead.
This is the sentence that can cost the most money to ignore. Suburban states: It is imperative that the water heater tank be filled with water before operating the water heater. Operation of the water heater without water in the tank may result in damage to the tank and/or controls. This type of damage is not covered by the limited warranty.
After a freeze, that turns into a two-step check that costs nothing: fill the tank and watch every outlet on it, including the anode rod threads and the pressure relief valve, with the water cold and the system pressurised. Then, and only then, fire it. A tank that has already split will show itself when it is full and cold, and finding it that way is a great deal cheaper than finding it with a burner underneath it.
A tankless heater is a different machine with its own freeze behaviour. Suburban's on-demand manual states that its freeze protection cycles the burner for five seconds when the water temperature falls below 41 degrees Fahrenheit, and that the protection only works if the gas supply is on, gas is available and electrical power is on. A tankless unit with the gas off and no power has no freeze protection at all, which makes the drain the only protection there is.
A winterised coach is not a freeze-proof coach, and the failures in a drained system are specific because they are the places draining does not reach. Every one of them is a place water sits by design:
The order to check them in is the order above, and the instrument is the same: bring the water system up, watch the pump, and fix what it points at.
Freezing damage is excluded, and it is excluded in writing, in the owner manual of the coach itself. Three makers' manuals say it in nearly the same words:
The component makers exclude it too. SHURflo's pump warranty is void if water is allowed to freeze in the system at all, and residential faucet makers exclude damage from freezing water in their own warranties. That makes the drain the cheapest insurance there is, and the reason it is worth doing at the end of every season rather than in an emergency.
Cost after a freeze is decided by how far the water got, not by how cold it was, and the range is unusually wide because it starts at a washer and ends at a tank.
The cheap end is fittings and small parts: a supply line, a faucet cartridge, the toilet's water valve, a pump strainer bowl. These are parts you can hold in one hand, and the labour is the searching rather than the fitting.
The middle is the pump. A pump head or a whole pump sits above fittings and below anything involving a tank, and a diaphragm assembly seized by frozen water is a pump problem rather than a fittings problem.
The expensive end is the water heater tank, which is a replacement rather than a repair, and the ice maker's solenoid valve on a fridge whose back has to come off to reach it. A tank or a fridge that has to be pulled out of its cabinet is the shape of freeze damage that gets close to the value of the appliance.
Two things move the number up. Damage discovered by firing the water heater rather than by filling it, because a tank that fails under heat can take the controls and the surrounding cabinetry with it. And water that ran unseen for weeks inside a floor or a wall, because then the repair is the floor or the wall rather than the plumbing.
Makers put the trigger at 32 degrees Fahrenheit, and the manuals say to winterise when the coach will be exposed to temperatures at or below it, not after the first hard freeze. The order that protects a system is the one in the winterising guide: tanks and low-point drains first, then every faucet to let air in, then the water heater drained and bypassed, then antifreeze in every trap and a drained, dried ice maker line.
Two additions to that job, because they are where a winterised coach still fails: empty the pump head itself, by disconnecting its ports and running it briefly, and deal with the ice maker line behind the fridge, which no winterising routine that ignores the fridge ever reaches.
The winterising guide covers the job that prevents this one, in order, with the antifreeze quantities. If the water heater has been drained, refilled and still will not heat, the water heater guide works the fault from the free checks inward. If the pump is running but nothing is coming out anywhere, the 12-volt guide has the voltage tests that separate a pump fault from a supply fault, and if water has reached the 120-volt side, outlets and GFCI covers the shock risk before anything else.
Turn the water pump off and open a tap before the system thaws. That gives the water somewhere to go and means a crack cannot spray under pressure while you are standing next to it. Then warm the living space so the system thaws from the inside out, and only afterwards bring the pressure back and watch the pump for a leak.
No. An open flame or a heat gun on a line is how a plumbing repair becomes a fire, and the foam and plastics around an RV water line do not tolerate it. Warm the space the plumbing runs through, open the cabinet doors so the heat reaches it, and let the ice melt on its own.
With every tap closed and nothing switched on, a pump that keeps running or keeps cycling is losing pressure somewhere, and after a freeze the places to look are a split housing and a fitting that has started to weep. The pump is the instrument here: it tells you a leak exists before water reaches the floor. The makers' own troubleshooting names the pump housing for cracks and a diaphragm assembly seized by frozen water.
Partly. The Plastics Pipe Institute, which is the technical body for PEX, states that its flexibility gives it excellent freeze break resistance and that it can expand and return to its original diameter. The same report does not address fittings at all, notes that ice blockages can create enough pressure to split the pipe, and warns that PEX systems should not be intentionally subjected to freezing. So the tube often survives and the parts holding water are the risk, which is not the same thing as a system that tolerates a freeze.
On the maker documents read here, no. Jayco's owner manual says repairs due to freezing are not covered by warranty and gives 32 degrees Fahrenheit as the point at which the RV should be winterized. KZ RV states that any problems resulting from freezing are not covered, and Venture RV lists loss or damage to the plumbing system caused by freezing as an exclusion. The pump maker goes further: freezing damage to the pump voids its warranty.