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Minimum horizontal distance between water/domestic lateral lines for townhouse project in California

kyap88

Civil/Environmental
Mar 5, 2025
5
Hi, I am working on a Townhouse project in Sunnyvale, California. Does anyone know the minimum horizontal distance/spacing between water/domestic lateral lines? Thank you.

CK
 
Something like this help?
1741308561926.png
 
Last edited:
Thanks for the reply. This is referring to the distance between sewer and other utility pipes, I am trying to figure the spacing between 1" water service lines or if they can be placed next to each other or stacked. :)
 
It's up to you and is more of a serviceability / installation and repair issue compared to any "code" requirement, though someone somewhere will have invented a separation distance just to be difficult.

no reason why you can't get 2,3,6 or more and just tie them all together with zip ties if they are PE reels.
 
Thanks for the reply. I would just assume some distance and the contractor would have the flexibility to adjust in the field.
 
kyapp88…

Have you asked the City? That's the place to start. The City's requirements must, at a minimum, conform to state law, but they could have more restrictive requirements. I did a quick search on Sunnyvale's website and did not find anything relevant, but they must have something in writing, even if it's only a reference to state law.

For your guidance, I have attached the following in a .zip file:
  • A memo from the California State Water Resources Control Board titled "Separation of Water Mains and Non-Potable Pipelines" (Dec. 14, 2017). This memo is from my electronic archives. I downloaded it in 2021.
  • California Code of Regulations Title 22, §64572. I downloaded this webpage today.
  • Guidance Memo No. 2003-02 from the California Department of Health Services (mentioned in the memo above as being superseded). This is from my electronic archives. I downloaded it in 2021. I also have a much earlier paper copy in my physical archives. I did not look to see if the California Department of Public Health (the successor to the Department of Health Services) has an updated version of this memo to replace the superseded version. I included this document because it has diagrams showing how to separate pipelines based on the then-current regulations. Even though the Guidance Memo has been superseded, I still find it useful.
  • A technical specification from the nearby City of San Bruno, which appears to follow the superseded Guidance Memo No 2003-02. This technical specification is undated, but I downloaded it today, so it is current. Perhaps Sunnyvale has a similar technical specification.
 

Attachments

  • Pipeline Separation.zip
    1.7 MB · Views: 3
kyapp88…

Have you asked the City? That's the place to start. The City's requirements must, at a minimum, conform to state law, but they could have more restrictive requirements. I did a quick search on Sunnyvale's website and did not find anything relevant, but they must have something in writing, even if it's only a reference to state law.

For your guidance, I have attached the following in a .zip file:
  • A memo from the California State Water Resources Control Board titled "Separation of Water Mains and Non-Potable Pipelines" (Dec. 14, 2017). This memo is from my electronic archives. I downloaded it in 2021.
  • California Code of Regulations Title 22, §64572. I downloaded this webpage today.
  • Guidance Memo No. 2003-02 from the California Department of Health Services (mentioned in the memo above as being superseded). This is from my electronic archives. I downloaded it in 2021. I also have a much earlier paper copy in my physical archives. I did not look to see if the California Department of Public Health (the successor to the Department of Health Services) has an updated version of this memo to replace the superseded version. I included this document because it has diagrams showing how to separate pipelines based on the then-current regulations. Even though the Guidance Memo has been superseded, I still find it useful.
  • A technical specification from the nearby City of San Bruno, which appears to follow the superseded Guidance Memo No 2003-02. This technical specification is undated, but I downloaded it today, so it is current. Perhaps Sunnyvale has a similar technical specification.
Thanks for the reply and providing the information!
 
It's up to you and is more of a serviceability / installation and repair issue compared to any "code" requirement, though someone somewhere will have invented a separation distance just to be difficult.

no reason why you can't get 2,3,6 or more and just tie them all together with zip ties if they are PE reels.

There are specific requirements almost everyone for this. If the inspector finds improper installation, the Contractor will have to correct it.

In California, the minimum horizontal distance between a water line (domestic lateral) and a sewer line running parallel to it is typically 10 feet. This separation is measured from the outside of each pipe.

Key points about water and sewer line separation in California:
  • 10 feet separation: This is the standard distance between parallel water and sewer lines.

  • Vertical separation: When crossing, the water line should be positioned higher than the sewer line, with a minimum vertical separation of 1 foot.

  • Check local codes: While 10 feet is the general guideline, always consult local building codes in your area for specific requirements.
 

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