Updated April 2026
ADU Utility Hookup Cost: $0–$35,000
Water, Sewer, Electric & Gas Connection Costs — Everything You Need to Know
Quick Answer
ADU utility hookups cost $0–$35,000+ depending on whether you share connections with your main house or install separate meters. California waives utility connection fees for ADUs under 750 sq ft.
Cost by Utility Type
Water Connection
- Shared meter with main house$0–$500
- Separate meter required$3K–$8K
- New service line to street$5K–$15K
CA: ADUs <750 sf exempt from connection fees
Sewer Connection
- Connect to existing lateral$500–$2K
- New sewer lateral required$5K–$15K
- Capacity/connection fee (750+ sf)$3K–$12K
CA: ADUs <750 sf exempt. Septic: $10K–$12K
Electrical Service
- Sub-panel from main house$1.5K–$3.5K
- Main panel upgrade$2.5K–$5K
- Separate meter & service$4K–$10K
Timeline: 4–8 weeks for utility company approval
Gas Service
- Extend existing gas line$500–$2K
- Separate gas meter$2K–$5K
- All-electric ADU (no gas)$0
Trending: all-electric with heat pump HVAC saves gas meter cost entirely
Total Utility Cost by ADU Type
| ADU Type | Utility Cost Range | Why |
|---|---|---|
| Detached ADU | $8,000–$25,000 | Needs all new utility runs; farthest from main house connections |
| Attached ADU | $3,000–$12,000 | Taps into existing systems through shared wall; shorter runs |
| Garage Conversion | $2,000–$8,000 | Often shares existing service; electrical already present |
| JADU (under 500 sf) | $1,000–$5,000 | Minimal new connections; built within existing home footprint |
Costs include all utilities. Separate meters add $3,000–$10,000 to any scenario. Updated April 2026.
Separate Meters vs. Submetered vs. Shared
| Factor | Separate Meters | Submetered | Shared Service |
|---|---|---|---|
| Upfront Cost | $3,000–$10,000 | $300–$900 | $0 |
| Monthly Management | Tenant pays utility directly | You read meter & bill tenant | Included in rent |
| Best For | Rental ADUs | Cost-conscious rentals | Family / multigenerational use |
| Pros | Clean tenant billing, avoids tier pricing, lower legal risk | Low upfront cost, fair billing possible | Lowest cost, simplest setup |
| Cons | High upfront, utility company coordination | Owner handles billing, legal gray area in some cities | Owner absorbs all utility costs, tier pricing risk |
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Get Your EstimateCalifornia Utility Fee Waivers (SB 13)
| ADU Size | Connection Fee Treatment | Status |
|---|---|---|
| ADU under 750 sf | All utility connection fees waived | Fully Exempt |
| ADU 750 sf and larger | Fees capped proportional to ADU size ÷ primary home size | Proportional |
| JADU (under 500 sf) | All fees waived, including school fees | Fully Exempt |
Fee waivers apply to connection/capacity fees charged by the city — not to actual construction costs. Always verify with your local utility company, as policies and fee schedules vary. The SB 13 waiver runs through December 31, 2026.
6 Ways to Save on Utility Hookup Costs
Go All-Electric
Skip the gas meter entirely. Use a heat pump for HVAC and water heating, plus induction cooking. Eliminates $500–$5,000 in gas connection costs.
Build Under 750 sf
In California, staying under 750 sq ft waives all utility connection fees automatically. Can save $3,000–$20,000 in fees alone.
Share the Water Meter
If your city allows it (most do for family-use ADUs), sharing the main house's water meter costs only $0–$500 vs. $3,000–$8,000 for a separate meter.
Place ADU Close to Existing Connections
Every foot of distance increases trenching costs at $25–$75 per linear foot. Siting your ADU near existing utility entry points can save thousands on underground runs.
Install Solar Panels
Solar offsets ongoing electricity costs. Combined with an all-electric ADU, solar can eliminate monthly utility bills almost entirely and may qualify for federal tax credits.
Use Low-Flow Fixtures
Low-flow toilets, showerheads, and faucets reduce water consumption, lowering monthly bills and potentially avoiding sewer capacity fee triggers at some utilities.
Monthly Utility Operating Costs
| Utility | Monthly Cost (600 sf ADU) | Notes |
|---|---|---|
| Electricity | $90–$160 | Higher if electric heat/cooking; solar reduces significantly |
| Water & Sewer | $40–$70 | Shared meter may trigger higher tier pricing |
| Gas | $20–$50 | N/A for all-electric ADUs |
| Trash & Recycling | $30–$50 | Often bundled with city services; may share with main house |
| Total | $150–$300/mo | For a 600 sq ft ADU |
Tip on tier pricing: Many utilities use tiered pricing where higher usage triggers higher per-unit rates. When an ADU shares a meter with the main house, combined usage may push both households into the most expensive tier. Separate meters keep each unit in lower tiers, which can partially offset the upfront meter installation cost.
Frequently Asked Questions
How much does it cost to connect utilities to an ADU?
Total costs range from $0 to $35,000+ depending on your setup. Sharing existing connections with the main house costs almost nothing ($0–$500). Installing fully separate meters for all utilities on a new detached ADU can run $8,000–$25,000. The biggest variables are distance from the main house (trenching at $25–$75/ft) and whether you need a new service line from the street.
Should I get separate meters or shared utilities for my ADU?
For rental ADUs, separate meters are strongly recommended. Tenants pay their own bills directly, which eliminates billing disputes and protects you from unexpected utility costs. For family use — parents, adult children, or multigenerational households — sharing meters is the simplest and cheapest option. Submetering ($300–$900) is a middle ground where you install internal meters and bill the tenant yourself, though this is legally complex in some jurisdictions.
Are utility connection fees waived in California?
Yes. Under California's SB 13, all utility connection and capacity fees are waived for ADUs under 750 sq ft. JADUs (under 500 sq ft) also have all fees waived, including school fees. For ADUs 750 sq ft and larger, fees must be proportional to the ADU's size relative to the primary dwelling — not the full fee charged for entirely new construction. This waiver is in effect through December 31, 2026. Always confirm with your local utility company as implementation varies.
How much are monthly utilities for an ADU?
Monthly utility costs for a 600 sq ft ADU typically run $150–$300 total. Electricity runs $90–$160/month, water and sewer $40–$70, gas (if applicable) $20–$50, and trash $30–$50. All-electric ADUs with solar panels can significantly reduce or eliminate electricity costs. Actual amounts depend heavily on climate, tenant habits, and whether utilities are shared or metered separately.
Can I share my water meter with the ADU?
Usually yes. Most municipalities allow ADUs to share the main house's water meter at a cost of only $0–$500. However, some cities require separate meters for rental ADUs, and some water districts charge capacity fees regardless of meter sharing. If you share a meter and rent the ADU, be aware that combined usage may push your household into higher water pricing tiers. Always verify with your local water utility before assuming you can share.
Do I need a separate electrical panel for my ADU?
Yes. Every ADU requires at minimum its own dedicated sub-panel, even when sharing the main house's electrical service. A sub-panel costs $1,500–$3,500 to install. If the main house has undersized electrical service (100-amp panels are common in older homes), you may need a main panel upgrade ($2,500–$5,000) before the ADU load can be added. A fully separate electrical meter and service — required for most rental ADUs — costs $4,000–$10,000 including utility company fees.
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