How Can You Winterize Your Plumbing System?

Outside the house

The discharge line deserves a second look every year. A line that freezes at the outlet leaves the pump running against a blocked pipe, which ends pumps early and floods basements during a February thaw.

• Disconnect every garden hose — a connected hose traps water in the bib and is the single most common cause of a split
• Shut the interior stop for each hose bib if you have one, then open the outside spigot to drain it
• Add insulated faucet covers on bibs that are not frost-free
• Check that the sump pump discharge terminates well away from the foundation and does not sit in a low spot that can ice over
• Clear leaves from window wells and grade so meltwater runs away from the house
• Shut off and drain irrigation systems according to the manufacturer's procedure

More on how that failure shortens pump life is in our guide to sump pump life expectancy.

Inside the house

A steady thermostat matters more than most people expect. Deep overnight setbacks save a little on gas and cost far more when a kitchen line on an exterior north wall gives out.

• Insulate pipes in crawl spaces, unheated garages, attics and along exterior walls
• Close crawl space vents and seal obvious drafts near pipe runs
• Find and label your main shutoff, and make sure the valve actually turns
• Open vanity and sink cabinets on exterior walls during a deep freeze so room heat reaches the pipes
• Keep the thermostat at a steady temperature rather than deep setbacks overnight in extreme cold
• Check the water heater for corrosion at fittings and confirm the relief valve discharge pipe is intact

Heating equipment that protects the plumbing

Winterizing plumbing and servicing heat are the same job in a Chicago winter. A furnace that quits on the coldest night of the year is a frozen-pipe event, not just a comfort problem. A boiler system with air in the loop leaves cold radiators and cold rooms where pipes run.

Getting heating equipment looked at in the fall, while parts are available and schedules are open, is the cheapest insurance in the checklist.

Furnace, boiler and thermostat work is on our heating services page, and the repair-or-replace thresholds we use are in

signs your furnace needs repair vs. replacement.

If the house will be empty

• Never set the heat below the mid 50s, even for a long absence
• Shut the main water valve and open a low fixture to relieve pressure in the lines
• Ask someone to check the house during extended cold, especially after a power outage
• Consider a freeze alarm or a low-temperature alert if you travel every winter
• Confirm the sump pump works and that any battery backup has a battery under five years old

If a pipe does freeze

A pipe that froze once will freeze again in the same spot. Once things are dry, it is worth fixing the reason — insulation, a draft, or a run that never should have been in that wall.

• Shut the main water off before thawing anything, so a split does not become a flood
• Open the affected faucet so melting water has somewhere to go
• Warm the area with a hair dryer or space heater — never an open flame
• Watch the pipe as it thaws and call if you see a bulge, a split or water appearing

Frequently asked questions