Skip to Main Content


rocks and boot

Sump Pump Discharge Guidelines: Why You Shouldn’t Run Your Sump Pump into the Sewer Line 

Too often, Complete Basement Systems finds problems with sump pumps where the previous sump pump installer ran the pump’s discharge into the home’s sewer line. Most homeowners don’t know about this. It’s common for homeowners not to know much about their home’s sump pump system, which is why problems like this can often go unnoticed for years. 

However, if you experience a problem with the sump pump discharge, you’ll find out almost immediately because the sewer line will often back up directly into your own home. From understanding the concept of a sump pump discharge line to learning more about your own, here’s everything you need to know about sump pump discharge. 

What Is a Sump Pump Discharge? 

Many people don’t know much about sump pump systems, including what a sump pump discharge line is in the first place. Here’s what a sump pump discharge line does for your basement.  

  • Releasing Day-To-Day Water from Your Basement 

Your sump pump discharge line will release the day-to-day water that would otherwise accumulate in your basement. Part of a solid basement waterproofing system is understanding that it’s unreasonable to assume you won’t have any water that comes into your basement. In fact, allowing some water to come in and drain out will help alleviate hydrostatic pressure on your walls, which can otherwise cause them to crack. 

The problem is that when water accumulates in your basement, it will often just remain there, causing water-related problems and humidity concerns until you remove it. A sump pump can take the water and pump it back out of the basement. The discharge line is how the sump pump removes water entirely from the building. Without the discharge line, you would have nowhere for the water to go once you pumped it out.  

  • Helping with Water from Rain and Natural Disasters 

When it rains or floods, the water table will rise. You may even have water that rushes through the streets and around your home’s foundation. This water will have an immense amount of pressure on your home’s foundation. Unfortunately, if you ignore the water’s pressure on your home’s foundation, it can end up destroying your basement or crawl space walls. This is one of the reasons homes in flood-prone areas typically have flood vents, which allow the water to enter and exit the basement or crawl space more freely. 

This might seem counterintuitive, but it’s actually an important part of making sure your home stays safe. If you refuse to allow entry to the water, your home’s walls may literally cave in under the weight and strength of the water. However, you also need some way to pump it back out, or it may stay in your basement or crawl space after the flood is over. That’s where a sump pump and its discharge line come into play. They help keep your home structurally stable, regardless of issues with flooding and raining outside.  

  • Avoiding Floods in the Basement or Crawl Space 

There’s always a chance that you may end up with a plumbing flood at some point. Plumbing lines can burst either in the general home or in your crawl space or basement, spewing water everywhere. Water is always going to pull itself down through gravity, which means it’s common for that water to enter the crawl space or basement even if that’s not where it originally started out. Even the most well-waterproofed crawl space or basement areas can then end up with large amounts of water. 

What’s the answer to this problem? First and foremost, you need a sump pump. Even for homes that don’t typically have flooding or excess rain problems, a sump pump will provide some protection against internal floods that may occur. The sump pump discharge line will ensure the water in your basement or crawl space, no matter where it comes from, won’t remain there. By removing it from the internal areas and sending it out, you can ensure you won’t have lasting flood damage. 

The Dangers of Running Your Sump Pump into the Sewer Line 

What’s the risk of running a sump pump into the sewer line? It’s just water, right? Unfortunately, that isn’t the case.  

  • Overflow from the Community 

The first danger is that of overflow from the entire community. Specifically, when you run your sump pump into the sewer line, it goes into the sewer treatment systems with all the other sewer water, which may include both dirty and clean water. The treatment plant of your local sewer system can only handle so much water. If it receives more water than it’s able to handle, the treatment plant will overflow into local streams and rivers. 

This is exactly what would happen if every community member ran their sump pump into the sewer system. The sewer system doesn’t account for the sump pump discharge line because it’s not legal for you to run the discharge line into the sewer. If everyone were to run their sump pump discharge line into the sewer, it would quickly overflow the treatment plant, causing raw sewage to run into local water sources even when they’re operating at a normal capacity. 

  • Overflow During a Natural Disaster 

Sure, if every person ran their sump pump discharge line into the sewer system, it would be a serious problem. However, it’s important to note that even just a few people running their sump pump system into the sewer system can cause the same problem during a natural disaster. That’s because your sump pump is likely to pump only a small amount of water on a regular basis, but it will pump much more water during a natural disaster. 

If even a few people decided to run their sump pump discharge into the sewer system, it may overflow as soon as there’s a flood that requires a substantial amount of sump pump discharging into that system. On the contrary, if you run the discharge line as it’s supposed to be run into your home’s yard, you’ll reunite the floodwater with the rest of the water as it runs through the streets and out of your home.  

  • Overflow in Your Own Home 

One serious problem that can happen when you run your sump pump discharge line into the sewer system is that the entire system then relies on your sewer system. This is a problem because it can certainly backfire if the sump pump system is trying to run when it’s unable to push water out to the sewer. More than likely, you’ll end up with a water overflow somewhere else in your home where the sewer system backs up. 

For example, if there’s a plug in your sewer’s drain line normally, you may not be able to flush toilets or run your drains properly. However, if there’s a plug in your sewer’s drain line and your sump pump discharges into the sewer system, it’s going to push water into the home’s sewer system. That can cause toilets and drains to overflow, literally making sewer water gush out throughout your entire home. This is both disgusting and incredibly detrimental to your home’s structural stability. 

Why Do Plumbers Run the Sump Pump into the Sewer Line? 

If there are so many problems with putting the sump pump into the sewer line, why do some plumbers continue to do it? There are a few reasons that an unsavory individual may choose to take the easy way out here. 

  • It’s Easier  

Quite simply, it’s easier to run the sump pump into the sewer line than it is to ensure that it’s running into a sump pump discharge system that the initial plumber set up. After all, the sewer system is already set up in your home, and the sump pump discharge system would have to be a new construction from the plumber. If the plumber only wants to save time and energy, they may make the decision to run the sump pump discharge into the sewer line. 

Of course, this doesn’t account for the fact that you may end up with problems from the sump pump down the line. Most commonly, someone who’s trying to cut corners by running your sump pump into the sewer system doesn’t really care about whether you end up having problems in the future. Instead, they just care about making it appear as though they fixed your problems right now. This is why it’s so important to get an installation expert who really cares about your problems holistically.  

  • It’s Cheaper 

Although creating a sump pump discharge system isn’t extremely expensive, it’s true that it is cheaper overall. Not only does the plumber not have to purchase the elements of the discharge system, but they also don’t have to spend time installing the sump pump discharge system. That makes it much cheaper for the plumber to just run the sump pump discharge line into the sewer system, as it saves both time and physical materials the plumber may have to pay for. 

The problem with this argument typically arises down the line when you end up having more problems. Sooner or later, you’ll almost certainly have to run your sump pump into a proper discharge system. Regardless of the way in which you discover your sump pump issues, you’ll probably have to call another expert out. That means paying additional money for a fix that should have been part of the initial sump pump installation.  

  • It’s Rarely Discovered by the Homeowner  

Lastly, many unscrupulous plumbers assume you’ll never really find out. It’s true that most homeowners don’t know a lot about their sump pump system. That means that many homeowners assume the plumber did what’s best. Even if the plumber is straightforward with you about running your discharge line into the sewer, they may assume you don’t know it’s bad to run the discharge line directly into the sewer. 

This is exactly why it’s often so important to learn more about your home’s system before you request a fix. Whether the fix is part of your sewer system, your basement, your crawl space, or something completely different, it’s up to you to learn about that system on your own before you get an expert to fix the problem. With more knowledge, you’re less likely to have someone scam you. 

What’s the Right Option? 

When you install a sump pump, it does need to discharge somewhere. However, discharging the sump pump into the sewer system isn’t the right answer. How should your sump pump discharge that extra water? 

Most commonly, sump pump experts recommend having it pump to an external discharge line, which then goes out of the home and into the yard toward a downward slope. When the discharge line ends, it should be far enough away from the home that the water doesn’t pool around your home’s foundation again. 

This is more work than just putting the sump pump discharge line into your home’s sewer system. However, it’s both the right thing to do and the legal thing to do. You should make sure that whoever’s installing your sump pump knows they need to do just that. 

Opt for a Professional for a Better Sump Pump Result 

When someone chooses not to run the sump pump outside the home like intended, it’s almost always because of laziness. It’s important that when you install the sump pump, you have a professional that won’t cut corners. Cutting corners may save you a few dollars up front, but it can lead to real problems both for yourself and for the community as a whole. 

Whether you currently have a sump pump and you’re concerned about the discharge system or you need to install a brand-new sump pump, Complete Basement Systems knows how to do it the right way the first time. Contact Complete Basement Systems to get a free estimate on installing your home’s sump pump today.

Serving Greater Denver area, Colorado Springs, Eastern Colorado, and parts of Nebraska and Wyoming

Colorado Springs, CO

707 County Line Rd.
Palmer Lake, CO 80133

Denver, CO

4686 Ivy St
Denver, CO 80216