How Much Does Bathroom Plumbing Rough-In Cost in Walnut Creek, CA? (2026)

Average Cost

$2,636–$4,384

Materials

$597–$1,275

Labor (East Bay)

$1,431–$2,097

Labor rates in East Bay are +20% compared to Sacramento Metro baseline.

A bathroom plumbing rough-in installs all the behind-the-wall and under-floor plumbing for a new or remodeled bathroom before drywall and fixtures go in. This includes drain lines (toilet flange, shower/tub drain, lavatory drain), vent piping tied into the existing vent stack, and hot/cold supply lines stubbed out for each fixture. Rough-in work requires a permit and must pass inspection before walls are closed. We coordinate with your general contractor to ensure plumbing is completed on schedule.

Walnut Creek is located in Contra Costa County (East Bay). Upscale suburb with mid-century to modern homes and condos. The local utility provider is PG&E.

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City

Fixtures

Materials Included

ABS Drain Pipe & Fittings (2" & 3")3 set

$180–$390

ABS Vent Pipe (1.5" & 2", per 10 ft)9 stick

$108–$225

PEX Supply Lines (1/2" hot & cold, per 50 ft)6 roll

$120–$240

Toilet Flange (ABS, with stainless ring)3 each

$30–$75

Shower Drain Assembly (2" no-caulk)3 each

$54–$135

Stub-Out Valves, PEX Fittings & Test Caps3 set

$105–$210

Labor(East Bay +20%)

Licensed Plumber9h @ $114–$168/hr

$1,026–$1,512

Plumber's Helper7.5h @ $54–$78/hr

$405–$585

Contractor Markup30%

0%Avg 30%100%

Materials

$597–$1,275

Labor

$1,431–$2,097

Markup

$608–$1,012

Estimated Total Cost

$2,636 – $4,384

$879–$1,461 per unit

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California Building Code

California Plumbing Code requires each fixture to be individually vented (or use approved AAV — Air Admittance Valves — where local jurisdiction allows). Toilet drain must be 3" minimum, shower 2" minimum, lavatory 1.5" minimum. Horizontal drains require 1/4" per foot slope. Rough-in must pass inspection before concealment.

Project Timeline

Layout & Floor Marking

30-45 min

Mark fixture locations on the subfloor (toilet flange 12" from wall, shower drain center, lavatory drain position). Verify measurements against the bathroom plan and confirm vent stack location.

Drain & Waste Piping

3-5 hrs

Cut through the subfloor or slab as needed, install the main drain line with proper slope, set the toilet flange, shower drain, and lavatory trap arm, and connect to the existing waste stack.

Vent Piping

1.5-3 hrs

Run vent pipes from each fixture up through the wall framing and tie into the existing vent stack or run a new vent through the roof. Each fixture must be properly vented to prevent siphoning.

Supply Line Rough-In

1.5-2 hrs

Run PEX hot and cold supply lines from the manifold or nearest supply point to each fixture location. Install stub-out elbows with test caps for the lavatory, toilet, and shower valve.

Pressure Test & Inspection Prep

30-45 min

Pressure test the supply lines to 80 PSI and water test the drain system. Install test plugs on all drain openings. Prepare for the rough-in plumbing inspection before drywall installation.

Materials Breakdown

Material	Qty	Unit	Unit Cost	Total
ABS Drain Pipe & Fittings (2" & 3")	3	set	$60–$130	$180–$390
ABS Vent Pipe (1.5" & 2", per 10 ft)	9	stick	$12–$25	$108–$225
PEX Supply Lines (1/2" hot & cold, per 50 ft)	6	roll	$20–$40	$120–$240
Toilet Flange (ABS, with stainless ring)	3	each	$10–$25	$30–$75
Shower Drain Assembly (2" no-caulk)	3	each	$18–$45	$54–$135
Stub-Out Valves, PEX Fittings & Test Caps	3	set	$35–$70	$105–$210

Bathroom Plumbing Rough-In in Walnut Creek — FAQ

What does 'rough-in' plumbing include?+

Rough-in includes all drain/waste/vent (DWV) piping and water supply lines installed inside walls and under floors before drywall. Fixtures (toilet, sink, shower) are installed later during the 'trim-out' phase.

How much does bathroom plumbing rough-in cost?+

A standard 3-fixture bathroom (toilet, sink, shower) rough-in costs $2,500-$5,000 in NorCal. Adding a bathtub or second sink adds $500-$1,000 per fixture. Slab foundations cost more due to concrete cutting.

Do I need a permit for bathroom plumbing rough-in?+

Yes. All new plumbing rough-in requires a permit and passes a rough inspection before walls are closed. The inspector checks pipe sizing, slope, venting, and connections.

Can I add a bathroom where there isn't one?+

Yes, but it requires extending drain, vent, and supply lines to the new location. The further from the existing plumbing stack, the more work and cost involved. A basement or slab bathroom may need a sewage ejector pump.

How long does bathroom rough-in plumbing take?+

A standard 3-fixture rough-in takes 1-2 days. If concrete cutting is needed (slab foundation) or a new vent stack must be run through the roof, allow 2-3 days.