Utilities for a Del Mar ADU
| Item | Del Mar rule |
|---|---|
| Connection fees | ADUs aren't new residential uses for connection fees; a new connection fee applies only to ADUs outside the house or an existing accessory building, proportionate to size and fixtures |
| Conversions | Existing structure with the right meter size: no new water or sewer connection fees |
| Sprinklers | Not required if the house has none |
| Ministerial limit | Expanding sewer, wells, fire protection capacity or septic needs a discretionary CDP |
| Submittal | Show water and sewer easements, services, connections and sprinkler status |
Source: DMMC §30.91.030, §30.91.040(Q)-(S).
Checklist
- Sewer lateral location and condition
- Meter size
- Panel capacity
- Drainage on slopes
- Flood zone elevation for equipment
The sewer lateral video
Before a new ADU sewer line connects to the house's lateral, Del Mar requires the existing lateral to be videoed and certified clear of obstructions or damage by a licensed plumber. The video and report go to the Director of Public Works. If the lateral is damaged beyond repair, a new lateral must be installed to serve both the house and the ADU.
What the plans must show
- Existing and proposed site drainage: pipes, catch basins and similar
- Details of any new sewer line: elevations, pipe material, cleanouts, trenching, backfill and the connection detail
- Utility locating before excavation, with an Underground Service Alert mark-out
- Demolition notes on shutting off utilities and temporary power, if a structure comes down
Connection fees under state law
The HCD handbook says ADUs built from existing space, and JrADUs, aren't treated as a new residential use for connection fees or capacity charges unless built with a new house. Where a fee applies, it must be proportionate, based on square footage or drainage fixture units compared with the house.
Utility checklist
- Sewer lateral video scheduled early
- Gravity route from ADU kitchen and bath to the lateral
- Panel capacity for a full kitchen
- Separate address requested
- Fire sprinklers only if the house requires them
Also checked Oct 14, 2026: Del Mar ADU Application Packet (Rev. 2024) · HCD ADU Handbook (March 2026).
Sources, checked Oct 14, 2026: Del Mar Municipal Code Chapter 30.91 (June 2025).
Questions
Does Del Mar require a sewer inspection for an ADU?
Yes. The existing lateral must be videoed and certified by a licensed plumber before the ADU connects, per the city's ADU application packet.