San Jose’s ADU Boom is Creating New Opportunities—But Don’t Overlook These Critical Plumbing Requirements
San Jose permitted over 460 ADUs in 2023, up from around 330 in 2020, marking a significant surge in accessory dwelling unit construction across the city. This boom is transforming backyards throughout Silicon Valley, but while homeowners are excited about the potential rental income and property value increases, many are discovering that plumbing considerations can make or break their ADU project.
Understanding San Jose’s ADU-Friendly Landscape
San Jose offers same-day permit issuance for projects with accurate and complete site-specific plans and related documents, making it one of the most streamlined ADU approval processes in California. With recent amendments, the majority of the 180,000 single-family homes in San Jose could qualify for an ADU. The city has even become the first in the state to allow homeowners to sell ADUs separately as condominiums, opening new investment opportunities.
However, this rapid expansion means more homeowners are encountering the complex reality of ADU plumbing requirements—an area where cutting corners can lead to expensive delays and code violations.
Essential Plumbing Considerations You Can’t Ignore
Water Supply and Fixture Requirements
The California Plumbing Code requires an ADU to have a Clothes Washer Connection, and its location must be shown on the Plot Plan. ADUs are small living units with a kitchen and bathroom, which means your plumbing system must accommodate multiple water-using fixtures while maintaining adequate pressure and flow.
ADU plumbing systems must include properly sized supply lines, typically 3/4-inch or 1-inch diameter pipes, to guarantee adequate water pressure, with shut-off valves at key points including the main connection and before each fixture.
Sewer Connection Complexities
One of the most challenging aspects of ADU plumbing involves sewer connections. You cannot connect new sewer lines of your ADU to the cleanout at the back of the main dwelling unit because it would result in maximum fixture units that exceed the limit set by the California Plumbing Code section 703.2.
Projects must provide a Site Plan showing the Point of Connection to the Sewer Line, including pipe size and type. For every 50 feet of distance, the sewer line must descend 1 foot to operate without a pump, otherwise you’ll need to pay about $5,000 for a sewage pump.
Utility Connection Options
You can use the same utility connections as your main home or install separate meters, but the decision impacts both upfront costs and ongoing maintenance. California law states that ADUs shall not be considered new residential uses for calculating local agency connection fees or capacity charges for utilities, and for certain ADUs, local agencies cannot require new or separate utility connections.
Why Professional Plumbing Expertise Matters
With San Jose’s booming ADU market, it’s tempting to rush through the planning phase, but plumbing mistakes can be costly. ADUs must pass foundation, framing, electrical, plumbing, and final inspections before occupancy, and plumbing violations can halt your entire project.
When you need expert guidance for your ADU plumbing project, partnering with an experienced plumber san jose residents trust can save you time, money, and frustration. Sugar Bear Home Services performs fast, reliable, and affordable repairs for homeowners in South San Francisco, with over twenty years of experience and a reputation for commitment to honest pricing and exceptional service.
Planning Your ADU Plumbing Project
Working with an experienced professional to prepare construction plans is recommended, as ADU plans involve many technical codes and working with an experienced ADU professional will save you time in the long run. Homeowners need to apply for a building permit, and depending on project specifics, additional permits such as electrical, plumbing, or mechanical might be required.
Key Steps for Success
- Produce water fixture counts as required for any ADU project, which helps determine the appropriate water meter size and ensures existing water service can accommodate new construction
- Locate the existing sewer, determine the nearest point for tie-in, and calculate the required “fall” or downhill slope of sewage pipe required to achieve proper flow
- Ensure compliance with all applicable codes and regulations, including structural integrity, electrical wiring, plumbing, and energy efficiency through proper inspections
Don’t Let Plumbing Challenges Derail Your ADU Dreams
Most ADUs in San Jose cost between $150,000 and $300,000, depending on size, finishes, location, and whether new utility connections or upgrades are needed. While plumbing represents a significant portion of these costs, proper planning and professional installation ensure your investment pays off.
Sugar Bear Home Services provides plumbing, HVAC, and electrical services with attention to detail and commitment to customer satisfaction, offering quick, reliable, and affordable services for emergency repairs or routine maintenance. As a locally owned company serving South San Francisco and surrounding areas, they understand the unique challenges of Bay Area ADU construction.
San Jose’s ADU boom presents incredible opportunities for homeowners, but success depends on getting the fundamentals right from the start. By understanding plumbing requirements, working with experienced professionals, and planning carefully, you can join the thousands of San Jose residents who are successfully adding value to their properties through well-designed ADUs.