St. Louis winters rarely stay cold for long, but they tend to arrive in sharp snaps that drop temperatures fast and hold them below freezing overnight. Most frozen pipes in St. Louis homes do not fail in the middle of the house. They fail in the places closest to the outdoors or the places that lose heat first, and those spots are usually easy to find before the cold arrives.
Where freezing usually starts
Walk through your home with a cold night in mind and mark the places where pipes run through air that is not heated the way the living space is.
- Exterior walls, especially on the sides of the house that take the wind
- Unheated garages and utility rooms, including the space around a water heater or filter housing
- Crawl spaces and open basement rim joists, where cold air can enter through gaps
- Attic runs and pipes near garage doors or exterior door thresholds
- Outdoor hose bibs, which are connected to the same supply as the rest of the house
Find your shutoffs before you need them
Know where the main water shutoff is and confirm that it turns. Some older valves stiffen with age, so turning them gently once a year helps prevent surprises. If your outdoor spigots have their own interior shutoffs, find those too and label them. When a pipe splits during a freeze, the fastest way to limit damage is to close the valve that stops water from reaching that section of the house.
Prepare outdoor spigots
Outdoor faucets are a common source of freeze damage in St. Louis because the pipe behind the wall runs straight to the outside. Before the first hard freeze, take these steps:
- Disconnect garden hoses and store them in a dry place.
- Close the interior shutoff for that spigot if one exists.
- Open the outdoor faucet so any remaining water can drain out.
- Cover the faucet with a fitted foam cover for the rest of the season.
Protect pipes inside the home
Indoor pipes near exterior walls come next. On cold nights, open the cabinet doors under kitchen and bathroom sinks so warm room air can reach the plumbing. Keep the thermostat at a steady setting instead of letting the house cool down during a long absence. If there are gaps where pipes enter the house, a little caulk or foam sealant can reduce the cold air that gets in.
Unheated garages and utility rooms
Equipment in unheated spaces often needs more attention than the pipes do. A water heater, a softener, or a filter housing sitting in a cold garage can be damaged by water that freezes inside it. Before a cold spell, check whether any equipment sits in a space that could drop below freezing. If it does, follow the manufacturer's cold-weather guidance and consider whether the space can be kept warmer. If you use a space heater, keep it well clear of stored fuel, cardboard, and fabric, and never leave it running unattended.
If a pipe freezes
A frozen pipe often shows no sign until you turn on a faucet and get a trickle or nothing at all. Do not use an open flame to thaw a line. Warm the pipe slowly with a hair dryer or a space heater placed at a safe distance, starting at the faucet end and working toward the frozen section. Keep the faucet open while you thaw so melting water has somewhere to go.
If you see water spraying from a pipe, or a wall stays wet with no obvious source, close the main shutoff right away. A burst pipe can release a great deal of water quickly. A licensed plumber can tell you whether a section needs repair. When you hire for that work, confirm the person holds a current license and carries insurance.
Check for hidden leaks after a thaw
Once a frozen line is back in service, watch for a crack that did not show up right away. Look at the floor under sinks, the base of the water heater, and the ceiling below upstairs bathrooms. Find your water meter and note its reading while no fixtures are running. If the reading keeps moving, water is leaking somewhere in the system.
Before the first freeze checklist
- Disconnect and drain outdoor hoses
- Cover exterior spigots
- Test the main shutoff
- Seal gaps where pipes enter the house
- Open cabinet doors on exterior walls during cold nights
- Check equipment in unheated spaces
- Keep a dry towel and a flashlight near the shutoff area
Plan this work in St. Louis early in the fall, before the nights get sharp. This page is an independent reader resource and does not replace advice from a licensed professional about your specific home.