A sagging sewer line can become a serious problem if you don’t fix it. Here’s what you can expect.

One flush. Two flushes. Three flushes. Four.

Once again, you have found yourself standing next to the toilet, pushing the lever and staring as the you-know-what spins round and round but refuses to go down. Don’t worry, it’s not you—it’s your sagging sewer line.

Then again, maybe you should worry. If something is wrong with your sewer line, you know it’s going to be expensive to fix. But just like your clogged toilet, a sewer line belly is not going to go away on its own.

In fact, it might just cause more damage if you let it sit, and that really stinks.

What is a sewer line belly?

A sagging sewer line, or belly, occurs when a dip forms at one or more spots along the sewer pipe. Most sewer lines use gravity to transfer waste from a home to the sewer. The water you send down the drain carries the solid waste down a sloping pipe that leads from your home to the main sewer system. Sometimes, the slope of a sewer line gets disrupted, which prevents the water and solid waste from moving freely to its destination.

What causes a sagging sewer line?

A sewer belly has many possible causes. Sometimes, the soil that supports a portion of the pipe settles, and over time the line begins to sag. Seasonal temperature changes, excessive rain, and poor soil compaction at the time the pipe was laid—all of these factors can contribute to a sagging sewer line. Other times, tree roots slowly push down against the soil and the sewer pipe.

When your sewer line begins to sag, you can expect to experience some common—and often nasty—consequences.

3 Nasty Effects of a Sagging Sewer Line

Clogged Line

When you have a belly in your sewer line, solid waste can become trapped in the low-lying area of the pipe. As you send more and more waste down the drain, the solids can build up until your line is completely clogged.

Backed Up Sewer Line

If your sewer line is totally obstructed, you run the risk of a sewage backing up into your home. As you can imagine, the resulting mess is horrifying and can lead to the spread of nasty bacteria inside your house, which can become a health hazard if it is not properly cleaned.

Sewage Leak

Sagging sewer lines may also crack. When cracks form in your sewer pipe, the waste water can leak into your yard. Even a small crack can lead to big problems because the water that escapes can erode the soil and contribute to more severe sagging, which can contribute to further cracking, and on and on.

How to Fix a Sag in a Sewer Line

Homeowners may be unfamiliar with the fact that sewage waste is often moved using gravity. There are a number of issues that can happen with this type of system, such as sagging. While a sagging sewer line is fixable, the cost may vary depending on the repair method.

Why Sagging Sewer Lines Are a Problem

Sewer pipes are installed with a positive slope, because they are gravity-based and work to push waste away from your home. In most cases, the angle is somewhere around 1/4 inch of drop for every foot of piping. However, if you have limited space, the slope can be as small as 1/8 inch, even though this is not preferable.

A sag in a sewer line, also known as a belly, creates a pool that blogs sewage from being pushed away from your home. Eventually, if the sag is severe enough, it can lead to clogs that block the entire pipe.

Improper soil compaction and natural soil shifting can cause the pipe to sag, which can lead to a significant risk of leaking or breaking.

Dig and Replace Method

The traditional method for replacing a sagging sewer line is known as the dig and replace method. As the name implies, a contractor will dig down into your property until the sagging section of pipe is exposed, then repair the pipe and backfill the trench. In many cases, this method costs about $60 per foot of piping that has to be replaced, but other factors can make it even more expensive. For instance, if the contractor has to pull up asphalt or concert to access the pipe, it can be quite expensive.

Trenchless Sewer Pipe Replacement

Over the years, we have learned how to fix a sag in a sewer pipe using new methods. These methods include in-line expansion and sliplining. These methods usually cost between $40 and $80 per foot and don’t require digging up your property.

How to Fix a Sag in a Sewer Pipe Under the House

In some homes, the sewer pipes are accessible from the basement or crawlspace. Sewer pipes are heavy, so if they are not secured properly to the structure of your home, they may cause the rest of the sewer line to sag. Sometimes this happens when the home slowly settles into the soil.

Homeowners may be able to fix this problem on their own, but in most situations, it is best to hire a trained and licensed professional to avoid causing unnecessary damage.

Should I repair my sagging sewer line?

It may be tempting to put off sewer line repairs when a sag occurs, but homeowners should use caution. When you try to save money by putting off repairs, it can cost you more later, since problems tend to worsen over time.

Want to prevent extensive damage from a sagging sewer line? Get an inspection today!

A sewer line belly is one of the last things you want to experience. For your peace of mind, if you suspect your sewer line may be in trouble, we suggest that you get it inspected.

Let Custom Plumbing of Arizona help you determine if you have a sagging sewer line. Contact us today to get the help you need.

Posted on Categories Emergency Plumber, Plumbing Service & Repair Phoenix AZTags Leave a comment on Your Sagging Sewer Line Is a Disaster Waiting to Happen

Every single drain and pipe in your home leads to one place: the main sewer line to your home. This critical drain line allows all the water—and all the other stuff you put down the drain—to flow out of your home and into the sewer. Main sewer line repair and replacement are some of the very last things you ever want to experience.

And that begs the question. Is there a way to avoid such a fate?

Over time, pipes can break down and rupture, and the main sewer pipe is no exception. However, knowing some of the top causes of main line damage can certainly help! To give you a chance to prevent this from happening to you, here are the top four reasons you could end up needing to repair or replace your main sewer line.

Flushing Un-flushable Debris

Some items, like toilet paper, are perfectly fine to flush down the toilet. Others, not so much.

Many people use their toilets to get rid of some truly bizarre things. Sometimes, someone’s toddler shoves a bunch of Barbies down there just to see what happens. If enough un-flushable objects make it all the way to the main line, they can cause serious damage by blocking your plumbing system’s ability to drain.

At that point, sewer line repair is next to inevitable.

A Sagging Sewer Line

Unless you oversaw the construction of your home, you probably can’t keep this problem from happening, but it doesn’t hurt to discuss it.

If the main sewer line is not laid properly (and sometimes even if it is), the soil beneath it may sink in certain spots. When soil compaction occurs, the pipe may sag. Here’s why this is a problem. When the main line forms a belly, water and waste can build up. When debris and material build up, erosion and blockages can occur.

Unfortunately, sewer line sags are difficult to detect without professional equipment. If you suspect you need sewer line repair, call a plumber to diagnose the problem first.


Trees are pretty amazing. They are also a plumber’s worst nightmare. That’s because tree roots stretch deep down into the soil searching for a source of water. When tree roots find a home’s sewer line, they sometimes press against the pipe until it breaks.

Homes with older ceramic sewer lines are more likely to have problems with tree roots, but with proper sewer line repair using more modern materials, you can ensure it never happens again.


You know you are not supposed to, but you do it anyway. We are probably all guilty of pouring grease down the drain at some point, but here’s a friendly reminder of why you should avoid it at all costs.

When you pour hot grease or oil down the drain, you might think that it can make it to where it needs to go. But as it travels down your plumbing, it cools and solidifies. What a mess.

Think You Need a Sewer Line Repair?

Get in touch with Custom Plumbing of Arizona today to diagnose your plumbing problem.

Posted on Categories Residential Plumbing ServicesTags