Plumbing for ADU

Plumbing for ADU garage conversions across San Diego County

A full ADU conversion requires new plumbing supply, drain, and vent runs to serve a kitchen, bathroom, and laundry that the original garage never had, and this work has to be roughed in and inspected before the walls close. We connect San Diego County homeowners with insured C-36 plumbing crews that assess the existing main home water and sewer connections, design the ADU plumbing layout, and complete all rough-in and finish plumbing under permit. Garage Convert SD is a referral service, insured but not licensed, cslb.ca.gov.

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Plumber running new water supply and drain lines under a San Diego County garage slab for an ADU kitchen and bathroom rough-in

What's included in this service?

Water supply connection from the main home line or a separate tap sized for the ADU fixture load
Under-slab drain and vent rough-in for an ADU bathroom and kitchen, including a slab penetration if required
Sewer connection to the existing lateral or to a new cleanout point depending on the garage location relative to the main line
Water heater installation for the ADU, either a tankless unit or a small tank depending on the unit size and usage
Kitchen and bathroom fixture rough-in and final trim including sink, shower or tub, toilet, and dishwasher connection
Laundry connection for a washer and dryer in the ADU if included in the conversion scope

When do you need this service?

You are building a full ADU and the garage has no existing plumbing to support a kitchen or bathroom
You are converting to a junior ADU and need a kitchenette connection to the main home plumbing
The existing garage water supply is a single outdoor hose bib and the conversion requires full hot and cold supply
You are adding a bathroom to a garage conversion and need under-slab rough-in before the flooring goes down
You want to add a laundry hookup in the ADU so the tenant has their own washer and dryer

What do homeowners ask about Plumbing for ADU?

How much does ADU plumbing cost in San Diego?

ADU plumbing for a garage conversion in San Diego County typically runs $12,000-$30,000 depending on the distance from the garage to the main sewer lateral, whether under-slab work is required, and the number of fixtures. A simple kitchenette connection for a JADU is at the lower end. A full ADU with kitchen, bathroom, laundry, and a new water heater is at the higher end. The crew assesses the existing connections at the on-site estimate.

Does ADU plumbing in San Diego need a permit?

Yes. Plumbing work for a garage conversion requires a plumbing permit in San Diego County, which is typically pulled as part of the overall building permit for the conversion. A licensed C-36 plumbing contractor pulls the permit and schedules the required rough-in inspection before the walls close and the final inspection after fixtures are trimmed out.

Can a converted garage ADU share the main home water heater?

It can, but it is rarely practical. Sharing a water heater means running a long supply line from the main home to the garage, which results in long wait times for hot water and heat loss along the run. A dedicated tankless water heater in the ADU is more efficient and gives the tenant independent hot water control. The crews we refer review both options at the on-site estimate.

Is a separate water meter required for a San Diego ADU?

California law does not require a separate water meter for an ADU. Many homeowners choose to keep a single meter and include water in the ADU rent. If you want separate billing, the San Diego County Water Authority or local water agency coordinates the meter split. The crew advises on the options when the plumbing scope is confirmed.