What Utilities Does an ADU Need? The Complete ADU Utility Guide

Setting up utilities for your ADU is a critical part of construction that significantly impacts both your budget and timeline. Understanding what utilities are required, how they connect, and what they cost will help you plan your ADU project effectively. This comprehensive guide covers every utility system you’ll need for a fully functional ADU in Los Angeles.

Required Utilities for Every ADU

Utility	Required?	Typical Cost	Notes
Water	YES	$2,500 – $8,000	Kitchen, bathroom, laundry connections
Sewer	YES	$3,000 – $12,000	Bathroom, kitchen drain connections
Electrical	YES	$5,000 – $15,000	New panel or sub-panel required
Gas (Natural)	NO (optional)	$2,000 – $6,000	For heating, cooking, water heater
Internet/Cable	NO (optional)	$500 – $2,000	Can share WiFi or run separate service
Trash/Recycling	YES	$0 (included in service)	Typically shares main house service

Water Service Setup

Connection Requirements

ADUs require potable water service for:

• Kitchen sink and dishwasher
• Bathroom sink, shower/tub, toilet
• Washing machine (if included)
• Water heater
• Exterior hose bibs

Water Connection Options

Option	Cost Range	Pros	Cons
Shared Meter (Most Common)	$2,500 – $6,000	Lower cost, simpler installation, no additional fees	Can’t bill tenant separately, owner pays all water
Separate Meter	$5,000 – $12,000	Can bill tenant directly, separate usage tracking	Higher installation cost, monthly meter fee (~$15)
Submeter (Private)	$3,500 – $7,000	Track ADU usage, bill tenant, no city meter fees	Must calculate billing, not official LADWP meter

Water Line Installation Process

Typical Steps:

1. Locate main house water line– Professional locating service
2. Excavate trench– 18-24 inches deep, from main to ADU
3. Install copper or PEX piping– 3/4 inch or 1 inch diameter
4. Connect to main line– Tee fitting or separate tap
5. Run to ADU– Underground conduit, proper depth and protection
6. Pressure test– Required inspection before covering
7. Backfill trench– Compaction required
8. Install shutoff valve– Separate control for ADU

Water Pressure Considerations

• Minimum pressure: 40 PSI required by code
• Typical LA pressure: 50-80 PSI
• Pressure booster needed if: Hillside property, existing low pressure, long runs
• Pressure reducer needed if: Over 80 PSI (prevents damage)

Booster pump cost:$1,200 – $3,000 installed

Water Heater Options

Type	Cost	Pros	Cons
Tankless (Gas)	$2,000 – $3,500	Endless hot water, energy efficient, space-saving	Requires gas line, higher upfront cost
Tankless (Electric)	$1,500 – $2,500	No gas needed, compact, efficient	High electrical demand (may need service upgrade)
Tank (30-40 gal)	$800 – $1,500	Lower cost, proven technology, simple installation	Takes up space, less efficient, can run out
Heat Pump	$2,500 – $4,000	Most energy efficient, rebates available	Higher cost, requires space and ventilation

Most popular for ADUs: Electric tankless (space-saving, no gas required)

Sewer & Drainage

Sewer Connection Requirements

ADUs must connect to existing sewer infrastructure for:

• Toilet drainage
• Shower/tub drainage
• Sink drainage (kitchen and bathroom)
• Washing machine drainage
• Dishwasher drainage

Sewer Connection Methods

Method	Cost	When Used
Gravity Flow to Existing Line	$3,000 – $8,000	ADU is uphill from existing sewer line, natural slope available
Sewer Ejector Pump	$4,000 – $12,000	ADU is downhill from sewer line, insufficient slope
New Cleanout Installation	$1,500 – $3,000	Required if no existing cleanout accessible to ADU
Sewer Main Upgrade	$8,000 – $25,000+	Existing sewer inadequate or damaged (rare)

Sewer Line Installation Details

Specifications:

• Pipe material: ABS or PVC schedule 40
• Minimum size: 4 inches for main drain
• Slope requirement: 1/4 inch per foot minimum
• Depth: 18-24 inches typical, deeper to meet main line
• Cleanout required: Within 5 feet of ADU, and at direction changes

Greywater vs Blackwater

Blackwater (sewage):

• Toilet drainage
• Must connect to sewer
• Cannot be diverted or reused

Greywater (drain water):

• Shower, bath, sink, laundry drainage
• Can be diverted for irrigation (optional system)
• Greywater system cost: $2,000-$5,000
• Reduces water usage, environmentally friendly

When Sewer Pumps Are Needed

Ejector/grinder pumps required when:

• ADU is below main sewer line elevation
• Insufficient slope for gravity flow
• Basement or below-grade bathroom
• Very long horizontal runs (over 100 feet)

Pump system includes:

• Basin/tank (typically 30-50 gallons)
• Pump unit
• Electrical connection (dedicated circuit)
• Alarm system (backup alert)
• Discharge pipe to sewer
• Maintenance access

Operating costs: Minimal electricity ($5-10/month)

Maintenance: Pump inspection every 3-5 years

Electrical Service

Electrical Load Requirements for ADUs

ADU Size	Typical Electrical Load	Service Size Needed
400-600 sq ft	40-60 amps	60-100 amp panel
700-900 sq ft	60-80 amps	100 amp panel
1,000-1,200 sq ft	80-125 amps	100-125 amp panel

Electrical Service Options

Option 1: Sub-Panel from Main House (Most Common)

Cost: $3,000 – $8,000

How it works:

• Tap into existing main house electrical panel
• Run underground feeder cable to ADU
• Install sub-panel in ADU
• Share main house electrical meter

Requirements:

• Main house panel must have adequate capacity
• Typically need 60-100 amps available
• Underground conduit from house to ADU
• Separate grounding system for ADU

Pros:

• Lower cost
• No separate meter fees
• Simpler DWP coordination

Cons:

• Can’t bill tenant for electricity separately
• May require main panel upgrade if insufficient capacity
• Shared electrical service

Option 2: Separate Electrical Service & Meter

Cost: $8,000 – $18,000

How it works:

• New service drop from street/alley
• Separate LADWP meter for ADU
• Independent electrical panel
• Completely separate from main house

Requirements:

• LADWP service application and fees
• May need new/upgraded transformer
• Dedicated meter socket
• Main disconnect at meter

Pros:

• Can bill tenant directly for electricity
• Independent service (no impact on main house)
• Required for AB 1033 condo conversion
• Better for larger ADUs

Cons:

• Much higher installation cost
• Separate monthly service fees (~$15)
• Longer LADWP coordination timeline
• More complex installation

Option 3: Main Panel Upgrade + Sub-Panel

Cost: $6,000 – $12,000

When needed:

• Existing main house panel is full or undersized
• Adding ADU would overload current service
• Main house has 100 amp service or less

Process:

• Upgrade main house service (typically to 200 amps)
• Install new main panel with space for ADU feeder
• Run sub-panel to ADU
• LADWP coordination for service upgrade

Electrical Connection Installation

Typical Underground Electrical Run:

1. Trench excavation: 18-24 inches deep
2. Conduit installation: PVC Schedule 40 or Schedule 80
3. Conduit sizing:
   • 60 amp: 1.25-inch conduit
   • 100 amp: 2-inch conduit
4. Wire installation:
   • 60 amp: 6 AWG copper
   • 100 amp: 2 AWG copper or 1 AWG aluminum
5. Grounding: Ground rod at ADU + equipment grounding conductor
6. Protection: Red warning tape 12 inches above conduit
7. Inspection: Required before covering

Essential Electrical Components in ADU

Component	Requirement	Cost
Main Panel	60-125 amp depending on size	$400 – $1,200
GFCI Outlets	Kitchen, bathroom, outdoor, garage	$15 – $30 each
AFCI Breakers	All bedroom circuits	$40 – $60 each
Smoke/CO Detectors	Hardwired, interconnected	$200 – $400 total
Dedicated Circuits	Kitchen (2), bathroom, laundry, AC/heat	Varies

Special Electrical Considerations

240V Circuits May Be Needed For:

• Electric range/cooktop
• Electric dryer
• Electric tankless water heater
• Central air conditioning
• Heat pump systems
• EV charger (if adding parking)

Energy Efficiency (Title 24 Compliance):

• LED lighting required
• Occupancy sensors in bathrooms
• Energy-efficient appliances
• Proper insulation of recessed lights

Natural Gas Service

Gas vs All-Electric ADU

Aspect	Natural Gas	All-Electric
Installation Cost	$2,000 – $6,000 for gas line	$0 (no gas line needed)
Water Heater	Gas tankless ($2,000-$3,500)	Electric tankless/heat pump ($1,500-$4,000)
Cooking	Gas range ($600-$2,000)	Induction range ($800-$2,500)
Heating	Gas furnace ($2,500-$4,000)	Heat pump/mini-split ($3,500-$6,000)
Monthly Operating Cost	Lower for heat/hot water	Higher in winter, lower in summer
Environmental Impact	Fossil fuel use	Cleaner (especially with solar)
Trend	Being phased out in CA	Increasingly required/preferred

Natural Gas Line Installation (If Choosing Gas)

Process:

1. Tap into existing gas meter/line
2. Trench from main house to ADU (18-24″ deep)
3. Install black iron or CSST (flexible) gas pipe
4. Size properly for appliance load (typically 3/4″ or 1″)
5. Pressure test (mandatory inspection)
6. Install shutoff valve at ADU
7. Connect to appliances (water heater, furnace, range)

Typical Costs:

• Gas line installation: $2,000-$4,000
• Additional appliance hookups: $200-$500 each
• Pressure testing: Included
• Permits: $200-$400

All-Electric ADU Trend

Why many ADUs are going all-electric:

• Saves $2,000-$6,000 in gas line installation
• No gas meter fees
• Aligns with California’s electrification goals
• Some cities restricting/banning gas in new construction
• Heat pumps now very efficient for heating/cooling
• Induction cooking is popular with renters
• Simpler utility setup

Recommendation:For most ADUs, all-electric is the better choice unless you have specific needs for gas.

Internet, Cable & Communications

Options for Internet/Cable Service

Option	Cost	Pros	Cons
Extend WiFi from Main House	$0 – $200	Free or very cheap, simple	May have weak signal, tenant uses your network
WiFi Extender/Mesh System	$150 – $400	Better signal, still uses main internet	Shares bandwidth, can’t bill separately
Hardwired Ethernet	$500 – $1,500	Fastest, most reliable, shares main internet	Installation cost, still can’t bill separately
Separate Internet Service	$1,000 – $3,000 install	Tenant gets own service and bill	Higher install cost, ongoing tenant responsibility

Running Data Lines to ADU

If running ethernet or coax cable:

• Bury in same trench as electrical (saves money)
• Use separate conduit (code requirement)
• Cat6 ethernet cable for future-proofing
• Install junction boxes at both ends
• Consider running extra for future needs

Cost breakdown:

• Conduit and wire: $300-$800
• Labor (if dedicated run): $400-$1,000
• Network equipment: $150-$400

Combined Utility Installation Strategy

Coordinated Trenching Saves Money

Smart approach:Dig one trench for multiple utilities

Single trench can accommodate:

• Water line (18-24″ deep)
• Sewer line (18-36″ deep, depending on slope)
• Electrical conduit (18-24″ deep)
• Gas line if applicable (18-24″ deep)
• Data/communications conduit

Spacing requirements:

• 12 inches minimum between water and sewer
• 6 inches minimum between other utilities
• Crossing utilities must be properly separated/protected

Cost savings:

• Separate trenches: $3,000-$5,000 each × 4 = $12,000-$20,000
• Combined trench: $5,000-$9,000 total
• Savings: $7,000-$11,000

Utility Installation Timeline

Phase	Duration	Key Activities
Underground Utility Location	1-2 weeks	Call 811, private locates, mark existing utilities
Trenching & Rough-In	1-2 weeks	Excavation, conduit/pipe installation
Rough Plumbing	1-2 weeks	Water and sewer connections, testing
Rough Electrical	1-2 weeks	Panel, wiring, testing
Gas Line (if applicable)	3-5 days	Installation and pressure testing
Inspections	3-7 days	Obtain approvals before covering
Backfill & Restoration	3-5 days	Cover trenches, compact, grade
Final Utility Connections	1 week	After construction, connect fixtures/appliances
DWP Service Activation	1-3 weeks	Final meter installation, service turn-on

Total utility installation timeline: 4-8 weeks(overlaps with other construction)

Total Utility Cost Summary

Budget Examples by ADU Type

600 sq ft Garage Conversion (Short Runs)

• Water: $1,500 (short run)
• Sewer: $2,500 (short run)
• Electrical: $3,500 (sub-panel)
• Gas: Skip (all-electric)
• Internet: $200 (WiFi extension)
• Total: $7,700

800 sq ft Detached ADU (All-Electric, Moderate Distance)

• Water: $4,000
• Sewer: $5,500
• Electrical: $7,000 (100A sub-panel)
• Gas: $0 (all-electric)
• Internet: $1,000 (hardwired ethernet)
• Total: $17,500

1,000 sq ft Detached ADU (Gas + Electric, Long Runs)

• Water: $6,000 (separate meter)
• Sewer: $8,500 (includes ejector pump)
• Electrical: $12,000 (separate service)
• Gas: $4,500
• Internet: $1,500 (separate service drop)
• Total: $32,500

Utility Costs as Percentage of Total Project

ADU Type	Total Project Cost	Utility Costs	Percentage
Garage Conversion (short runs)	$145,000	$7,700	5.3%
Detached ADU (moderate)	$195,000	$17,500	9.0%
Detached ADU (complex)	$275,000	$32,500	11.8%

Utility-Related Permits & Inspections

Required Inspections

1. Underground Plumbing Inspection– Before covering water/sewer lines
2. Underground Electrical Inspection– Before covering electrical conduit
3. Gas Line Pressure Test– Before covering gas lines
4. Rough Plumbing Inspection– Before closing walls
5. Rough Electrical Inspection– Before insulation/drywall
6. Final Plumbing Inspection– After fixtures installed
7. Final Electrical Inspection– Before Certificate of Occupancy
8. Final Building Inspection– Overall compliance check

Utility Cost-Saving Strategies

1. Go All-Electric– Save $2,000-$6,000 by skipping gas line
2. Share Meters When Possible– Save $5,000-$10,000 on separate meters
3. Coordinate Trenching– One trench for all utilities saves $7,000-$11,000
4. Optimal ADU Placement– Locate ADU closer to main house utility connections
5. Garage Conversions– Existing utilities nearby reduce connection costs 50-70%
6. Plan During Design– Route ADU location to minimize utility runs
7. Bundle Permits– Combined permit applications save time and fees
8. Use Qualified Contractor– Experienced contractors avoid costly mistakes and failed inspections

Ongoing Utility Costs (Monthly/Annual)

Typical Operating Costs for 800 sq ft ADU

Utility	Monthly Cost (Owner-Paid)	Annual Cost
Electricity (all-electric ADU)	$80 – $150	$960 – $1,800
Water/Sewer (LADWP)	$50 – $100	$600 – $1,200
Gas (if applicable)	$30 – $70	$360 – $840
Internet (if owner-paid)	$0 – $70	$0 – $840
Trash (typically shared)	$0	$0
Total (All-Electric)	$130 – $250	$1,560 – $3,000

Note: Most landlords have tenants pay their own utilities. If utilities are included in rent, charge $150-$250/month premium.

Get Professional Utility Planning

Proper utility planning is essential for a functional, code-compliant ADU that doesn’t blow your budget. The decisions you make about utility connections early in the design process can save thousands of dollars and weeks of time.

As Los Angeles ADU contractors and code compliance specialists, we can help you:

• Evaluate optimal utility connection strategies for your property
• Coordinate all utility installations in the most cost-effective way
• Navigate LADWP and other utility provider requirements
• Ensure all utility work meets code and passes inspections
• Resolve any existing unpermitted utility work before your ADU project
• Design and build your ADU from planning through completion

Start with our ADU Eligibility Checkand Cost Calculatorto understand your project scope and budget.

Bottom line: Budget $8,000-$20,000 for utilities on a typical detached ADU, less for garage conversions, more for complex sites or separate meters. Going all-electric and sharing meters with the main house provides the best value for most projects.