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Single-Family Home Tear Down & Rebuild

Can I Reuse an Existing Sewer Lateral for my New Home?

A sewer lateral is the pipe that connects your home to the public sewer main, which conveys all of the wastewater from your home to a sewage treatment plant.

Residential Sanitary Sewer System
Illustration of how a Residential Sanitary Sewer System works.


Typically, a new home project will propose a new sewer lateral connection from the home all the way to the sewer main in the street. This is the best option as you will have a sewer lateral that will last as long as your home for the next 30-50 years, possibly even longer.

With so many Tear Down & Rebuild Projects in Northern Virginia, it is common for the existing sewer lateral to be capped at the property line during demolition of the old home and reconnected to during construction of the new home.

Below is a Site Plan example of a typical tear down & rebuild project in Arlington, Virginia. The existing sewer lateral (highlighted in yellow) was capped at the property line during demolition and the new sewer line (highlighted in green) connected to the cap-off location during construction of the new home. This is the most cost-effective option as you will save the cost of tap-fees and having to pay a contractor extra to cut into the public street.

Site Plan for a home tear down and rebuild project.
Highlighted snippet from a DeMarr Engineering Site Plan. Pink = Existing 8” Sewer Main, Yellow = Existing 4” Sewer Lateral connecting to the existing 8” sewer main, Orange = Property Line, Green= Proposed 4” Sanitary Lateral from house to Property Line.

Vacant Lot vs. Tear Down & Rebuild

First we will need to determine if you have an existing sewer line to reuse. This will depend on if your project is a tear down & rebuild or vacant lot development. If your lot is vacant, you will have no choice but to install a sewer line all the way from the house to the public sewer main in the street and pay for county tap fees. If you purchase a lot to tear down the existing house and rebuild a new one, you most likely will be able to reuse the existing sewer.  

Advantages of Reusing an Existing Sewer Lateral

  • Savings on County Tap Fees.
  • Savings of not having to pay your utility contractor for a street cut to install a new sewer lateral in the Public Right of Way (Street & Sidewalk).
  • Less Permits and easier for construction.  

Disadvantages of Reusing an Existing Sewer Lateral

  • The portion of the existing Sewer Lateral in the street may not be in good condition and could have a high probability of failure in the next year or 5-10 years. You will have a new home with the uncertainty of how long the existing sewer lateral will last. 
  • If or when the existing sewer lateral fails, it will cost more to replace than if you replace during construction of the home. 
  • Extra cost of having to install an ejector pump for your basement bathrooms. The proposed basement is usually lower than the existing sewer lateral, meaning that your new basement will not be able to flow by gravity to the public sewer main and will need a pump for the basement bathrooms. 

Advantages of Installing a New Sewer Lateral all the way to the Main

  • Peace of mind knowing your sewer lateral will last as long as your new home.
  • The basement will most likely be able to make gravity from the house to the sewer main and not require a basement ejector pump. 

Disadvantages of Installing a New Sewer Lateral all the way to the Main

  • There will be an additional cost of cutting into the public street.
Elevation drawing of a DC Sanitary Sewer Line Connection
DeMarr Engineering elevation drawing of a typical sewer line connection in Washington, DC


If you need a contractor to install a new sewer lateral in Northern Virginia, we can refer you to our parent construction company DeMarr Construction to provide you with a quote.

As your Civil Engineering consultant and designer, we can help guide you through the process and provide information for you to decide what option is best for you. Before buying a property, we can help answer questions including: Do you have an existing sewer lateral? Is there a public sewer main available to connect to? Will I need a septic field? We can look into these questions with a Feasibility Study

If you are planning to build a new addition or home in Northern Virginia or Washington, DC, please contact us for a quote on your next Land Development project.

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