Accessory Dwelling Units (ADUs)

Do you have an existing home that has water service with the District and are planning to build an accessory dwelling unit (ADU) on your property? Find out how to secure water for your new construction unit below.

What is an ADU?

ADU stands for Accessory Dwelling Unit. It is an additional, self-contained housing unit that is secondary to the main residence on a single family home lot. It must have all features that are required in a standard residence (kitchen, bathroom, sleeping area, heat, etc.). ADUs are also known as granny units, in-law apartments and second units.

Does my new ADU require a new water service?

It depends on the type of ADU you are building. Conversion ADU (see definition below) do NOT require a new water service or Will Serve letter.

Download this ADU Requirements handout to access whether your ADU project is a “conversion” or a “new construction” ADU.

Conversion ADUs

Conversion ADUs (which are contained inside the existing square footage of a house or legal accessory structure) do not need a new water service and do not require Conditional and Unconditional Will Serve approval to proceed with the appropriate land use planning agency .

Process for New Construction ADUs

New Construction ADUs require a dedicated meter to serve the new unit and will require a Conditional and Unconditional Will Serve letter from the SqCWD Board in order to proceed with the building process. A detailed step by step flowchart of the steps to get new service outlines the process for getting a Will Serve letter and getting a new meter dropped. It is summarized as follows:

  1. Apply for Will Serve letter with New Water Service Application and $300 application fee. Meet with Conservation staff.
  2. Get Conditional Will Serve letter and proceed with the appropriate land use planning agency to get building permit.
  3. Get Unconditional Will Serve letter.
  4. Build.
  5. Pay Water Capacity Fees and Metering Fees. Enter into the Applicant Installed Service Agreement with Engineering.
  6. Install service and have service inspected by SqCWD building inspector.
  7. SqCWD will drop meters and service will begin.

Cost overview

Check out our New Water Service Fee Breakdown to see the fee breakdown for common residential developments (including ADUs). Costs are subject to change and are for reference only.

Have Questions or Want to Schedule an Appointment?

Contact Alyssa Abbey, Staff Analyst, by email or by phone at (831) 475-8500 x124.