ADU Plumbing Guide
ADU Plumbing Guide
Water supply, drainage, sewer, and water heater decisions for your California ADU.
Shared or separate utilities? Tankless or heat pump water heater? Here's how ADU plumbing works.
What is the minimum plumbing required for a legal ADU in California?
What are California's water conservation requirements for ADU fixtures?
How do drain lines work in a concrete slab ADU or garage conversion?
How does ADU sewer connection work in California?
What is a sewer lateral inspection and is it required?
What CALGreen requirements apply to ADU plumbing beyond fixture flow rates?
What is the DWV system and what happens if venting is improper?
What is seismic strapping for water heaters and why is it required everywhere in California?
What are the gas line requirements when an ADU uses gas appliances?
What are the most expensive plumbing surprises on ADU projects and how do you avoid them?
This information is general guidance for California ADUs. Requirements vary by jurisdiction — confirm the specifics for your project with your local building department.
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Please note: The pricing shown reflects MEP Plans USA’s own current flat-rate pricing only and is not intended to represent average market, competitor, or public pricing. We’re proud to offer some of the best flat-rate MEP prices in California.
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