Can a Sewer Line Freeze in Winter? What Loveland Homeowners Should Know

A properly buried sewer line rarely freezes, but it can happen. The City of Loveland and Larimer County both use a frost depth of 30 inches below grade in their building design criteria, so lines laid below that depth are normally protected by the ground above them. Problems tend to show up where pipe is shallower than it should be, exposed in a cold crawlspace or garage, or holding standing water in a sag.

With an average January low of 12.9°F and about 47 inches of snow a year, Loveland gets enough cold that the weak spots in a drain system can be tested, especially during a long cold snap.

Ground temperature changes slowly. Below the frost line, soil stays above freezing through the winter, and that is why codes set a minimum depth for buried pipe. Sewer lines also carry water that is usually warmer than the ground, from showers, dishwashers and laundry, and they drain between uses rather than holding water like a pressurized supply line.

Snow helps too. A blanket of snow insulates the ground, which is one reason the deepest frost often comes during cold spells with bare ground rather than after a big snowfall.

Shallow sections. Some lines were laid shallower than current standards, or the ground over them was lowered by later landscaping. Those stretches are the most exposed.

Bellies. A sag in the pipe holds water. If that low spot is near the surface, the standing water can freeze and block the line.

Exposed pipe. Drain lines that run through unheated crawlspaces, garages or along exterior walls can freeze, especially if a drip of water keeps trickling into them.

Vents and outdoor fixtures. In extreme cold, frost can build up inside a roof vent and restrict airflow, causing slow drains and gurgling. Outdoor cleanouts with damaged caps can let cold air and snowmelt in.

If drains slow suddenly during a hard freeze and other causes seem unlikely, a frozen section is possible. Stop running water so it does not back up into the house. If an accessible pipe in a crawlspace or garage is frozen, gentle warmth from a space heater kept at a safe distance, or a hair dryer, can help. Never use an open flame on pipes.

A buried line that freezes usually needs professional help to thaw it, and ice can hide another problem, such as a sag or partial clog that held water to begin with. Our page on emergency drain service Loveland explains what to expect when a drain problem cannot wait for regular hours.

A house that sits empty during a cold spell loses the warm water that normally flows through its drains. If a sewer line has any shallow or sagging sections, standing water there has more time to cool. If you travel in winter, keep the heat on, ask someone to check the house and run water now and then, and make sure no fixture is slowly dripping into a cold line.

The same advice protects supply pipes, which freeze more often than drains and can cause far more damage when they burst.

As snow melts, water can soak into the ground around a sewer line. In expansive clay soils, which the Colorado Geological Survey calls Colorado's most significant geologic hazard, that moisture can swell the soil and stress the pipe. Spring is a good time to notice whether drains are slower than they were in the fall.

A winter that ends with frequent clogs or gurgling is a reason to ask for a camera inspection, which can show sags, offsets or root growth before the next freeze.

Most Loveland homes never deal with a frozen sewer line, but the cold does find weak spots: shallow pipe, sags, exposed drains and fixtures that drip. A little preparation in the fall goes a long way, and a slow drain during a cold snap is worth taking seriously.

Loveland Drain Clean is a free referral service, and calls are answered 24/7. Call (970) 693-9705 and we will connect you with an independent local provider. Homes in southwest Loveland near the Big Thompson corridor are covered on our Mariana Butte Loveland drain cleaning page.