How much do Plumbing Plans cost?
Standalone ADU plumbing plans start at $995 for an ADU up to 600 SF and scale to $2,095 for 1,001–1,200 SF. Plumbing can be combined with another discipline from $1,195, or included in the Full MEP Package from $1,495.
Plumbing plan pricing by size
| ADU size | Plumbing only | With one more discipline | Full MEP (all three) |
|---|---|---|---|
| Up to 600 SF | $995 | $1,195 | $1,495 |
| 601–800 SF | $1,295 | $1,495 | $1,795 |
| 801–1,000 SF | $1,695 | $1,895 | $2,195 |
| 1,001–1,200 SF | $2,095 | $2,295 | $2,595 |
What the plumbing fee covers
- Water supply design — hot and cold distribution, pipe sizing, and fixture connections.
- Drain-waste-vent (DWV) layout with proper venting, slopes, and cleanouts per the California Plumbing Code.
- Water heater specification — typically a heat pump water heater or tankless unit sized to demand and Title 24 efficiency requirements.
- Fixture schedule and riser/isometric diagrams for kitchen, bathroom(s), and laundry.
- Gas piping where gas appliances are used, sized to BTU demand.
Why plumbing scales with square footage
Larger ADUs add fixtures — a second bathroom, a bigger kitchen, a laundry — and each fixture adds supply lines, drain and vent piping, and longer runs. More fixtures and longer runs mean more sizing calculations and more detailed riser and isometric drawings, which is reflected in each price bracket.
Add-ons and turnaround
The water heater on your plumbing plans must match the efficiency assumptions in your energy model, so pairing plumbing with the Title 24 report (+$240) keeps the two consistent. Turnaround upgrades are Priority +$299 (3 business days) or Expedited +$599 (1–2 business days); standard 5-business-day delivery is included.
What is not included
Our fee covers the drawings only. Significant site-driven work is separate and project-specific — for example a new sewer lateral, concrete slab cutting in a garage conversion, water-service upgrades, and especially utility water and sewer connection fees, which some California districts charge in the thousands to over fifteen thousand dollars. City permit fees are also separate.
Plumbing bundled vs. standalone
Most new-construction ADUs are best served by the Full MEP Package, where plumbing is included from $1,495 — far less than buying three separate single-discipline sets. A standalone plumbing order ($995 and up) is the right call when another discipline is handled elsewhere, such as an attached ADU that reuses the main house electrical and HVAC but still needs new water and DWV piping. Whichever route you choose, the plan fee is the same statewide with no sales tax.
Every plumbing order includes two revisions, city corrections, and permit-ready PDF delivery. See the pricing page or start an order.
Ready to Get Started?
If you’re planning a similar project, MEP Plans USA provides permit-ready Mechanical, Electrical, and Plumbing plans for California ADUs, garage conversions, additions, and single-family homes.
Please note: The pricing shown reflects MEP Plans USA’s current flat-rate pricing only and is not intended to represent average market, competitor, or public pricing. We’re proud to offer some of the best flat-rate prices in California.
- Flat-Rate Pricing
- City Corrections Included
- Two Revisions Included
- No Hidden Fees
- Fast Turnaround