illustration of home lateral

Your sanitary sewer lateral is the pipe that carries your wastewater from your home (toilets, sinks, showers, laundry, floor drains, etc.) to the public sanitary sewer main that is typically in the street.

Just like roofs and driveways, maintaining a lateral is the homeowners' responsibility. Some communities require homeowners to repair and maintain laterals from the house out to around the sidewalk or tree lawn, what's known as the right of way. In other communities, homeowners own the lateral from the house all the way to where it connects to the city's sewer system in the street. Check with your city to find out.

How Do Laterals Play a Role in Basement Backups?

Laterals are only supposed to carry the water you use in your house out to the city's sanitary sewer pipe. Cracks and leaks in laterals end up allowing groundwater into the sewer, which can overwhelm the overall system and cause stormwater and wastewater to back up in the sewer system and into people's basements.

illustration of a how a lateral works with your home

How Do I Know if a Basement Backup is From Too Much Rain or a Clogged Lateral?

If it's not raining and you get water backing up into your basement through the floor drain, there's a good chance you have a clogged lateral. The water that you used inside your home cannot get through the lateral and empty into the city's sewer out in the street.

Even if it is raining and you have water coming through the floor drain, you could still have a clogged lateral that needs to be cleaned out. When basement backups occur because the public sanitary sewer system is full, typically your neighbors will have the same problem at the same time. Contact your city or village department of public works right away so they can check to see if there are any problems with the public sewer in the street.

How Can I Tell if My Lateral is Cracked or Leaking?

If you have ever had to call a plumber to unclog your lateral, you most likely have a damaged and leaky lateral. Tree roots are always seeking water and end up growing through cracks in laterals. The roots end up catching things that are flushed or poured down the drains in your home, leading to a clogged pipe. You can tell when your lateral is clogged when water backs up into your basement through a floor drain, sink, toilet or other plumbing fixture during dry weather or wet weather. In dry weather, the water that is backing up is water you used in the home that cannot get out the lateral to the city's sanitary sewer in the street. During wet weather, water leaking into the lateral can start backing up into the basement since it can’t run out fast enough due to the blockage.

If you suspect problems with your lateral or you would just like the peace of mind, you can check for blockages, leaks, and cracks by having a plumbing company run a television camera through your lateral. You will be able to see any major problems right away. When your municipality looks for widespread problems in the sewer and laterals, they often use an environmentally friendly green dye to soak into the ground. When the camera views green water in the lateral, they know there are leaks in the pipe.

If you get a lateral inspection, make sure to get a copy of the video. You may want to get a second opinion on any problems that are diagnosed and potential solutions.

Sanitary Sewer Lateral Basics

How to Locate Your Lateral 

In your house: Your lateral starts where your house sanitary plumbing goes vertically into the basement or crawl space floor from the upper levels of the house. This large pipe is usually about 4” in diameter and made of cast iron or plastic and often referred to as the sanitary stack.  There is usually a branch from the pipe with a cap for access which is called the cleanout. Often the sanitary stack is located near the water service line and water meter. While not recommended, if your basement is finished, the sanitary stack is often covered by a wall or panel.

In your yard: Once you locate your sanitary stack inside the house, make a general reference from the location inside the house to a spot you can identify outside the house. You can do this by using a tape measure to measure the distance from the nearest corner or window of the basement and transfer this measurement outside the house. Once outside the house, use your reference point and measurement to estimate the location of the sanitary stack inside the house and look straight towards the street. This typically is the location of the lateral across your yard. This is only approximate. If any digging is planned by you or others in your yard, you need to have all utilities professionally located by contacting Digger’s Hotline.  

​​​​How to Acess Your Lateral

Typically, the interior of a home will have three (3) access locations:

Internal Cleanout: this is located on the sanitary stack or cast into the basement floor.

Exterior Cleanout: Not common in our area unless you have a long sanitary lateral (over 100’ from the street sewer to your house). If your sanitary lateral has been replaced or had repairs in the past, you likely do have an exterior cleanout.

Floor Drain: The floor drain is a plumbing fixture in your basement floor that accepts standing water near or around the drain.  The floor drain is another access point to your lateral.  The lateral should only be accessed by a professional plumber. The sanitary lateral is a direct connection to the public sewer including the gases, odors, and other undesirable elements that come to mind. Your house is protected from these elements with water traps on all plumbing fixtures. Accessing the lateral bypasses this feature and leaves an open pathway for gas, odors, etc. into your house. If you smell sewer gas in your house, the most likely source is a water trap that has dried out from non-use. Floor drains are particularly prone to this. Pour at least one gallon of water in all plumbing fixtures including toilets and floor drains. If odors persist, contact a plumber. 

photo of cleaning interior lateral pipe
photo of cleaning exterior lateral pipe
photo of basement floor drain

How Should I Maintain My Lateral?

If you need to have a contractor clean and cut roots out of your lateral on a regular basis, you should have your lateral video inspected every five to ten years. If you have never seen the inside of your lateral, having a video inspection is relatively inexpensive peace of mind. If the lateral is in good condition, there is no need to re-inspect for the foreseeable future. Newer laterals are made out of PVC, a high-strength plastic that is slightly flexible. PVC pipes for home laterals are typically in10-foot segments and have long-lasting, water-tight joints when installed properly. Plumbers started installing PVC laterals in Wisconsin in the 1970's.

Older laterals may be made out of clay pipes that were typically installed in two-foot sections with joints that either are not sealed or have seals that failed long ago. Clay pipe material is extremely durable over time, however, the pipes are susceptible to cracks and damage that lead to failure over time. Tree roots are the most common cause of damage.  

Maintain Your Lateral by Avoiding:
  • "Flushable" wipes, feminine hygiene products, cat litter, or other materials that do not easily break down or that can clump and clog your lateral.
  • Never pour or flush hard chemicals, drain cleaners, paint, oil, pesticides, cement, plaster, or medications down your drains.
Dont Pour Grease Down the Drain

FATS, OILS & GREASE - Do Not Pour Them Down the Drain!

Dispose of all fats, oils, and grease in the garbage. This includes butter, cooking oils, fry oil, oils and grease left from cooking meats and/or anything else that gels or solidifies at room temperature. While these will go down the drain or toilet when warm or with soap, they will all gel and solidify as they move down your lateral and the sewer when they cool down or when they mix with other water creating a clog that is very messy and difficult to remove.

When to Get Your Lateral Inspected

Consider hiring a plumber to perform a video inspection of your lateral if:

  • You have a basement back up through the floor drain or other basement fixtures
  • Evidence (debris around the floor drain or in a washtub) that water backed up particularly during wet weather or high use times (shower, laundry)
  • You have periodic slow-running drains or toilets, particularly during wet weather or high use times (showers, laundry)

Tips for a successful video inspection:

  • Choose a plumber who uses a sewer camera that can record the video inspection and includes a running footage counter
  • The plumber should record the full lateral video from the house access point to the mainline sewer connection
  • If obstructions or damage are found, have a report/video prepared by the plumber stating the findings and the location (footage) of the blockage or damage.  The footage counter allows you to go outside with a tape measure and estimate in your yard where the problem is and what might be in the way to fix it (trees, driveway, sidewalks, etc.)

Lateral inspection items that are noteworthy but don’t require immediate action:

  • Minor pipe sags (indicated by standing water in the bottom of the pipe)
  • Minor gaps in pipe joints
  • Minor roots, sediment, or groundwater deposits

Items that should be monitored (regular inspections and cleaning) and will likely require action sometime in the future:

  • Minor to moderate root intrusion and/or groundwater deposits
  • Pipe cracks
  • Recurring small amounts of sediment, soil, or gravel (less than a handful)
  • Offset pipe joints or breaks that are not disrupting a smooth flow of water

Items that need urgent attention:

  • Heavy root intrusion  
  • Broken, missing, or collapsed pipe
  • Soil or gravel in the pipe that is blocking the flow
  • Offset pipe sections that interrupt the smooth flow

What's the Fix if My Lateral Needs Repairs?

There are many newer repair techniques that do not require digging a large trench in your front yard. However, laterals with serious problems or multiple problems may require digging a trench to install a new pipe from the street to the foundation of your home.

  • Broken Clay Lateral

    Broken Clay Lateral

    Older laterals may be made out of clay pipes that were typically installed in two-foot sections. Joints and cracks on clay pipes tend to fail over time, allowing large gaps to permit excess water into the sanitary sewer system.

  • Open Trench Excavation

    Open Trench Excavation

    Crews dig a trench down to remove the old pipe, and lay a new one from your house out to the city's sewer in the street. In our area, this usually requires a trench that is 8 to 12 feet deep.

  • Cured in Place Piping

    Cured in Place Piping

    A flexible liner is prepared on the surface by soaking a fabric liner with a thick liquid resin. The inside of the lateral is cleaned to remove all roots and debris. The liner is then pulled into the lateral from either the cleanout in the house or from the public sewer. Once the liner is place, the liner is inflated to hold the shape of the inside of the existing pipe and allowed to cure and harden. Once cured, there is a new, smooth, continuous plastic pipe inside of the old pipe

  • Pipe Bursting

    Pipe Bursting

    Contractors dig a hole at each end of the lateral. Usually one hole will be in the street where the lateral connects to the sewer and the other hole will be just outside of the house or just inside the basement where the lateral passes underneath the foundation. A “bursting” head is attached to the new lateral pipe and attached to a cable that has been threaded through the old lateral pipe running from one hole to the other. The cable is pulled under high pressure through the existing lateral pipe with the bursting head breaking the old pipe and clearing the path for the new pipe as it passes from one hole to the other.