Can a Sewer Line Freeze?

Frozen pipes and frozen sewer lines are common winter plumbing issues for homes and businesses in cold climates. When the water inside sewer pipes cools to freezing and expands, it creates pressure on the pipe walls. Frozen sewer pipes can crack and burst, potentially flooding your home. Frozen sewer lines can also hinder water flow and cause frustrating plumbing backups. If your plumbing ices up when temperatures take a dip, some simple preventive measures may reduce the risk of freezing and help keep your home safe and dry.

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How Deep Are Sewer Lines Buried?

How deep your sewer lines are buried can vary, depending on your specific climate, along with local codes and regulations. Here's a breakdown of average sewer line depths based on location:

• Midwest. The Midwest is known for its cold winters, which means sewer lines should be buried fairly deep to prevent freezing. Typically, the lines are buried between 4 and 8 feet deep.

• Northwest. Climates in the Pacific Northwest vary from temperate to cold, depending on the season. Sewer lines in the Northwest are usually buried between 3 and 6 feet deep.

• Northeast. The Northeast typically experiences cold winter climates with heavy frost penetration. Sewer pipes are commonly buried between 4 and 7 feet deep.

• South. The Southern United States is known for warmer climates, which means sewer pipes are buried fairly shallow. In general, sewer lines are buried between 2 and 5 feet.

• Southwest. The climate in the Southwest is typically warm and comfortable. On average, sewer line depths range between 2 and 4 feet.

Can Sewer Lines Freeze?

Sewer lines can freeze when the water inside reaches freezing temperatures. Sewer lines and plumbing pipes are at risk of freezing when outdoor temperatures drop below 32 degrees Fahrenheit (0 degrees Celsius), and the risk increases as temperatures fall.

What Happens If a Sewer Line Freezes?

When the water inside a sewer pipe becomes stagnant and temperatures dip below freezing, sewer lines can freeze and expand. Since frozen water takes up more space when solid, the pressure and expansion can lead to damaged and cracked sewer lines. Constant pressure on your sewer lines can increase the risk of cracking and splitting, which can lead to flooding and other plumbing issues inside and outside the home.

Since sewer main lines are buried, it can be difficult to determine if they're frozen or damaged. However, the indoor pipes that connect to underground sewer lines may feel cold, or you may spot visible water leaks on interior walls or ceilings.

Some additional signs of frozen sewer pipes include slow-draining water and blocked drains in several fixtures in the home. You might notice strong, unpleasant odors around sink, shower or tub drains and gurgling noises coming from the toilet.

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How Can You Prevent a Sewer Line From Freezing?

While there's no way to predict when the winter temperatures will drop below freezing, there are some simple measures you can take that may help prevent frozen sewer lines. Here are some helpful solutions to keep your pipes protected during winter:

• Insulate pipes. If you have sewer line pipes running through your garage, crawl space or any other unheated area, it may be a good idea to have them insulated. Pipe insulation can add an extra layer of warmth when the temperatures drop and help reduce the risk of freezing.

• Ensure outdoor pipes are buried properly. All outdoor sewer pipes should be buried based on local regulations and the freezing depth, or frost line, of your region. Sewer line depths typically range from 2 to 8 feet. To help prevent frozen sewer lines, it's important to make sure your sewer lines are buried below the frost line for your location.

• Keep the water flowing inside. If the weather forecast predicts freezing temperatures, turn your interior faucets on at a trickle before you go to bed for the night. The constant flow of water may prevent the pipes from freezing.