How to keep your pipes from freezing in an Iowa winter

Frozen pipes are one of the few plumbing disasters that are almost entirely preventable, and Iowa gives us a long enough cold season that it is worth doing properly rather than hoping.

One thing to understand first, because it changes how you think about the risk: ice does not usually burst a pipe where it forms. The ice plug blocks the pipe, and continued freezing behind it builds enormous pressure in the trapped water between the plug and a closed faucet. The pipe fails at the weakest point in that section - which can be several feet away, in a spot that never froze at all.

Before the cold: the jobs worth doing in autumn

Disconnect the hose

The most common single cause of a burst we see. A hose left connected traps water in the bib and the short run behind it, which is inside the wall. Disconnect every hose, drain it, and shut off the interior valve feeding the bib if you have one. Frost-free hose bibs still fail if a hose is attached, because the hose stops them draining.

Insulate the vulnerable runs

Identify pipes in exterior walls, unheated basements, crawl spaces, attics and attached garages. Foam pipe sleeve is inexpensive and takes an afternoon. Pay attention to where a run passes near a rim joist or a foundation vent, because that is where cold gets in.

Seal the air leaks

Insulation slows heat loss; it does not stop cold air moving. A pipe in an insulated wall with an unsealed penetration nearby will still freeze because outside air is being drawn straight onto it. Spray foam and caulk around penetrations, dryer vents, sill plates and foundation cracks. This step gets skipped and it matters more than the insulation.

Deal with the garage and crawl space

Keep garage doors shut if there is plumbing in the wall. Close crawl space vents for winter. Fit foam covers to exterior bibs.

During a deep freeze

• Let a tap trickle. Moving water freezes far less readily, and an open tap also relieves the pressure build-up that actually bursts pipes. A pencil-thin stream from the fixture furthest from the main entry is enough. Run both hot and cold slightly.
• Open cabinet doors. Under kitchen and bathroom sinks on exterior walls, so room air reaches the pipes.
• Keep the heat on, and up. Do not set back at night during a hard freeze. If you are away, never below 55°F.
• Keep the garage closed. Obvious, and constantly forgotten.

If you are leaving the house empty

For a few days, leave the heat at 55°F and ask someone to check in. For a whole season, shut the main off, drain the system by opening the lowest and highest faucets, drain the water heater, and pour RV antifreeze into every trap including floor drains and toilet bowls so the traps do not freeze and crack.

A pipe has already frozen. Now what?

Signs: a tap that has slowed to a trickle or stopped entirely during cold weather, frost visible on an exposed pipe, or a section that is bulging.

1. Open the faucet that the frozen pipe feeds. This gives melting water somewhere to go and relieves pressure.
2. Apply gentle heat starting at the faucet end and working back toward the freeze. A hair dryer, a heat gun on low, or towels soaked in hot water. Never a blowtorch, never an open flame, and not a space heater left unattended.
3. Know where your main shutoff is and be ready. If a split has occurred, water will start moving the moment the plug clears.
4. Watch as it thaws. Reduced pressure after thawing, or the sound of water running with everything closed, means the pipe has split.

If the pipe is inside a wall or you cannot reach it, do not start opening drywall in a panic. We do pipe thawing and repair throughout the winter, and part of that job is watching the line come back under pressure to catch a split before it empties into your ceiling.

If it has already burst

Shut the main off immediately, open the lowest faucet in the house to drain the system, and cut power to any circuit near the water. Then call. Burst pipe repair is what our 24/7 line exists for, and there is no overtime charge on it - waiting until morning turns a plumbing repair into a restoration job.

The part most people skip

After a freeze, ask why that particular run froze. If a pipe froze once it will freeze again, and the answer is usually rerouting it, insulating it properly, sealing an air leak nearby, or fitting heat tape. Fixing the split without fixing the cause just books next January's appointment in advance.