September 11, 2026 · 3 min read
Why early and late season trips catch owners off guard
Alberta weather swings hard in spring and fall. A mild day in Calgary can turn into a frosty night once you're parked higher up in the foothills or the Rockies, and the city forecast won't tell you what a mountain campground will get. Check the forecast for the place you'll actually sleep, not the place you left from.
Most RVs are built for comfortable temperatures, not deep cold. Water lines often run along outside walls, through unheated compartments or under the floor, so they cool much faster than the living space. One short dip below zero may do little, but several hours of hard frost, especially with wind, can freeze the exposed parts of the system.
The parts that freeze first
The outdoor fresh water hose and the city water connection usually freeze first. Next is anything exposed underneath: low point drains, dump valves, the sewer hose and any lines in an open or poorly insulated underbelly. Outdoor showers and exterior wash stations are also at risk because their plumbing sits right behind a thin panel.
Inside, the trouble spots are lines tucked behind cabinets on exterior walls and the area around the water pump. The pump and its fittings can crack if water freezes inside them. The water heater holds a good amount of water, so it resists freezing while it's running. If it's switched off on a cold night, though, it can freeze and be damaged like any other part of the system.
Habits that keep water flowing on cold nights
Before dark, disconnect the outdoor hose, drain it and store it inside. Fill your fresh tank during the day and run off the onboard pump overnight, since on many units the tank sits in a better protected spot than the hose and inlet. Keep the grey and black valves closed and dump during the warmest part of the day, so the sewer hose drains empty instead of holding water overnight.
Run the furnace, not just an electric space heater. On many RVs the furnace pushes warm air into the underbelly or tank area. A space heater can keep the cabin warm enough that the furnace rarely kicks on, which leaves the plumbing bay cold. Open the cabinet doors under the sinks and in the bathroom so warm air reaches the lines. If your RV has tank heating pads, switch them on and watch your batteries, since the pads draw power.
If a hard freeze is coming, pour a little non-toxic RV antifreeze down each drain to protect the traps. Never use automotive antifreeze. Bring a jug of drinking water in case the lines freeze anyway. If they do, don't run the pump against a frozen line. Warm the area gently, and never use an open flame or a torch near plastic plumbing.
After a cold snap, and when to bring it to Horton
Frozen plumbing often doesn't leak until it thaws. Once it warms up, turn the pump on with every tap closed and listen. If the pump keeps cycling on and off, water is getting out somewhere. Look for drips under the rig, damp carpet or cabinet floors, low pressure at the taps, and water around the pump, toilet and water heater.
Small leaks behind walls and under floors can soak into the wood, and over time that leads to soft spots or delamination. Find them early instead of waiting until the end of the season. If you'd rather not pull panels yourself, or the leak is somewhere you can't reach, Horton RV Services in Calgary can track it down and repair it.
Cold nights are also hard on the furnace, water pump and water heater. If one of them isn't working right after a trip, bring the RV in and we'll diagnose it and source the right parts. If your season is ending, winterize before the RV sits through a freeze. One cold night in storage can undo all your careful habits at camp.
Common questions
How cold does it have to get before my RV water lines freeze?
There isn't one number. It depends on how long the temperature stays below zero, the wind, how well your underbelly is insulated and whether the furnace is running. A short dip just under freezing often does little. A long, windy night well below zero can freeze exposed hoses, valves and lines. Treat any forecast below zero as a reason to take precautions.
Can I leave my city water hose connected if the furnace is running?
It's safer not to. The furnace warms the inside of the coach, and sometimes the underbelly, but the hose and the outside connection sit in open air. Disconnect and drain the hose before night and use the fresh tank and pump instead. If you camp in the cold often, a heated hose rated for freezing weather is worth considering.
My water pump turns on by itself after a cold night. What does that mean?
When the pump runs with no taps open, the system is usually losing pressure. The most common causes are a leak, a cracked fitting, or a worn valve inside the pump. Switch the pump off, look for water under the rig and inside the cabinets, and get it checked before a slow leak damages the floor.