Why a Houston freeze breaks so many pipes
In the February 2021 storm, Bush Intercontinental fell to 13°F on February 16 and stayed below freezing for 44 hours straight, and the Weather Service summary lists power outages that lasted days and broken pipes across the region. In an ordinary year that station still sees about 11 nights at or below freezing, and in about 57% of years it reaches 25°F. Our own records show 146 frozen or burst pipe jobs since 2018.
Which pipes freeze first
Attic runs. Many slab homes here carry the water lines through the attic. A line above the insulation sits in outdoor air. Exterior walls. Kitchen and bath lines behind a closed cabinet. Hose bibs. Worse with a hose still attached. Exposed yard and garage lines. Above ground at the meter, along a garage wall, or under a raised floor. Water heaters in garages and attics. Tankless units on an outside wall. More on those below. Backflow preventers and sprinkler lines. Exposed on all sides; follow your installer’s steps for draining them.
Before the freeze: a checklist
Insulate. Foam sleeves on every pipe you can reach in the attic, garage and outside. Houston’s emergency management office says pipes that run outside or under a house should be wrapped. Disconnect hoses. Then cover each hose bib with an insulated cover. Open the cabinet doors under sinks on outside walls so room heat reaches the pipes. Keep the heat on. University of Illinois Extension says to leave the heat set no lower than 55°F, even if you’re away.
To drip or not to drip
It depends on who supplies your water. Houston Public Works has said it does not advise dripping faucets, because the City’s system runs on re-pump stations, not water towers, and mass dripping can pull down pressure across the system. Many MUDs and cities with water towers suggest a trickle. Check the name on your water bill and follow that provider’s freeze instructions.
Know where your main shutoff is
Find it while it’s warm, and turn it once to be sure it moves. On most Houston homes it’s the valve on the house side of the meter box at the curb, or a valve where the line enters the house or garage. The valve on the street side of the meter belongs to the utility. If you can’t find yours inside the City, 311 can help. A stuck valve is a small fix before a freeze; see water leak repair.
Tankless water heaters
Most tankless units have built-in freeze protection, but it runs on electricity. Navien says not to unplug the unit or close the gas valve in cold weather, and to drain it if power or gas will be off for an extended period. Rinnai says to keep power to the unit and, in a long outage, shut off the water and gas and open the drain valves as the manual shows. Navien’s limited warranty does not cover freeze damage. See tankless water heaters.
Heat for the house, safely
A furnace that sat idle since March is the one that won’t light on the first cold night. If it fails a test on a mild day, see furnace repair in Houston. Heat pump owners, see heat pumps. If the power goes out, the CPSC says to run a portable generator outside only, at least 20 feet from the house, never in a garage, and to keep CO alarms working.
Sources: National Weather Service, February 2021 storm lows · NWS February 2021 regional climate summary (PDF) · NWS Houston/Galveston heat and cold statistics (PDF) · Houston OEM, winter weather · KPRC 2, Houston Public Works statement on dripping · University of Illinois Extension, water pipes · Rinnai, freeze-protect your Rinnai product · Navien, tankless water heater freeze notice · CPSC, generators and carbon monoxide · Turbo Home Services job records (BluePro), 2018–Oct 2026. Updated November 2026.
