St. Louis winters are rarely long, but they are unpredictable. A run of mild afternoons can be followed by a sharp overnight drop, and that swing is when most cold-related water trouble starts. Pipes in exterior walls, outdoor spigots, and lines running through an unheated garage or crawlspace are the usual weak spots. This guide covers what to check before the cold arrives and what to do during a hard freeze.

Find the parts of the house that get cold

Before the first freeze, walk the house and note every place water runs close to outside air. In many St. Louis homes, that list includes:

  • Outdoor hose bibs and any spigot without an indoor shutoff
  • Supply lines along exterior walls, especially on the north or west side that gets little sun
  • Pipes in an attached garage, a basement window well, or a crawlspace near a foundation vent
  • A water heater sitting in an unheated garage or utility room
  • Irrigation lines and any backflow device above ground

Drain and disconnect outdoor fixtures

Take garden hoses off every outdoor tap before the first hard freeze. A hose left attached holds water in the valve, and that water can split the fitting when it freezes. If your spigot has an indoor shutoff, close it, open the outdoor faucet so the line can drain, and leave the faucet open through winter. If there is no indoor shutoff, use an insulated cover to slow freezing, but understand that a cover reduces the risk rather than removing it.

Sprinkler and irrigation systems need to be drained before cold sets in. A licensed irrigation service can blow out the lines and check the backflow device. If you handle it yourself, follow the control box instructions and make sure you know where each zone drains.

Protect exposed pipes before a hard freeze

Foam pipe sleeves are an inexpensive way to add some insulation to exposed runs in a garage or crawlspace. Heat tape can help on the most vulnerable lines, but use a product rated for pipes, follow the label closely, and plug it into a ground fault protected outlet. Do not leave heat tape wrapped over itself or pinned under insulation.

Open the cabinet doors under sinks on exterior walls so warm room air can reach the pipes. Keep your thermostat at one steady setting during the coldest stretch rather than turning it down overnight. When a hard freeze is forecast, let a faucet on the coldest side of the house run at a thin, steady trickle. The moving water helps keep the line from freezing solid, though it does add to your water use for those days.

Check the water heater and softener

A water heater works harder in winter because the water entering it is colder. Confirm that the temperature and pressure relief valve discharge pipe points toward a drain and is not blocked, and look for drips at the fittings and around the base. If the heater sits in an unheated space, a blanket made for water heaters can reduce heat loss, but check the manufacturer's guidance before covering any part of it.

If your home has a water softener, check the salt level during the winter and refill it before the tank runs low. Look at the brine tank for bridging, which is salt forming a hard crust that keeps water from reaching the salt below.

Know your shutoffs and meter location

Find the main shutoff valve and turn it slowly to confirm it moves freely. Many homes have it where the water line enters the house, often in a basement, crawlspace, or utility room. If your meter sits in an outdoor pit, keep the lid clear of snow and debris so it can be read and so the pit does not fill with standing water. Write down the shutoff location and keep it somewhere everyone in the household can find.

What to do during a hard freeze

  1. Open cabinet doors under exterior-wall sinks and keep the thermostat steady.
  2. Let faucets on the coldest side of the house run at a thin trickle.
  3. Watch for weak flow at a tap, which can signal a partly frozen line.
  4. If a pipe freezes, shut off the main at once, open the faucet nearby, and thaw the section with warm air from a hair dryer or a space heater placed safely away from the pipe.
  5. Never use an open flame or a torch to thaw a pipe, because it can damage the pipe and start a fire.

After the thaw

Once temperatures recover, check the house for signs of damage. Look under sinks, around the water heater, along the basement ceiling, and in the crawlspace for drips, damp drywall, or water stains. Turn the main back on slowly, open the outdoor spigots gradually, and watch the valve for spraying, which points to a split line that needs repair.

If water looks cloudy, tastes unusual, or runs discolored after a cold snap or a utility repair in your area, run the cold tap until it clears. If the change persists, a water test can show what is going on. Your St. Louis water provider can also tell you about planned work in your neighborhood, so it is worth checking their notices during the winter months.