What ADU Plumbing Actually Involves

More than just hooking up a sink: ADU plumbing is a full system build.

An ADU (accessory dwelling unit) is a secondary living space on your property, a backyard cottage, a converted garage, a basement apartment, or an addition above the garage. Portland has actively encouraged ADU development for years, and the city's permitting process is more streamlined than most. But plumbing an ADU is a serious job that touches your existing home's water and sewer connections.

ADU plumbing typically involves extending your home's existing water supply lines, tying into the sewer or drain system, installing a new water heater (or extending service from the existing one), and running gas lines if needed. Depending on the size and scope of your ADU, Portland Water Bureau may also require a new water meter and service connection. This isn't DIY territory. It requires a licensed plumber and proper permits from the start.

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Every Phase of ADU Plumbing: Handled by One Team

Rough-in through finish, Nolan coordinates it all.

PDX Plumber handles ADU plumbing from the ground up. Here's what's included:

- Water service connection: extending supply lines from your main home to the ADU, or coordinating a new meter connection with Portland Water Bureau when required - Drain, waste, and vent (DWV) rough-in: the network of pipes behind the walls that carry wastewater to the sewer. This has to be done right before framing closes up - Gas line installation: running gas to a water heater, range, or fireplace in the ADU - Water heater installation: tank or tankless, sized right for the ADU's load - Kitchen plumbing: supply and drain lines for the sink, dishwasher, and any appliances - Bathroom plumbing: toilet, shower or tub, vanity sink, all rough-in and finish work - Laundry hookups: hot and cold supply lines plus a drain for a washer - Permit coordination: we pull the required plumbing permits and schedule inspections so you don't have to manage that process - Final inspection and sign-off: all work is inspected and approved before the project closes

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Portland ADU Plumbing Permits: What You Need to Know

Permits protect your investment, and your ability to rent the unit legally.

Portland requires a mechanical or plumbing permit for any new plumbing work in an ADU. Skipping permits might seem like a shortcut, but it can block you from getting a certificate of occupancy. Which means you legally can't rent the unit. It can also create major headaches if you ever sell the property.

For ADUs that will function as independent dwelling units, Portland Water Bureau may require a separate water meter and a new service lateral (the underground pipe connecting your property to the city water main). This adds cost and timeline, but it also means the ADU's water usage is metered separately from the main house, a real advantage if you're renting it out.

PDX Plumber pulls all required plumbing permits and coordinates inspections. You focus on the build. We handle the paperwork that keeps it legal.

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Why Portland ADU Builders Trust PDX Plumber

Experience, licensing, and a reputation that speaks for itself.

ADU plumbing isn't a job for a generalist. It requires someone who understands both new construction rough-in work and the quirks of connecting to an existing residential system, often at the same time. Nolan brings 25+ years of plumbing experience to every ADU project, with a track record on kitchens, bathrooms, basements, and new builds throughout Portland.

Here's what every PDX Plumber ADU job includes:

- Oregon CCB licensed and fully insured - Upfront project pricing before work begins - Permit pulling and inspection scheduling included - Clean, on-time work that keeps your build on schedule - 5-star rated on Google and Facebook - Financing available for larger projects

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Three Steps to Start Your Portland ADU Plumbing Project

Simple process, even for complex builds.

Getting your ADU plumbing underway is straightforward:

1. Call or book a consultation: tell us about your ADU project, the scope, and where you are in the build process. 2. We assess the connection points, walk through permit requirements, and give you clear, upfront pricing. 3. We handle the rough-in, finish work, permits, and inspections so your ADU is ready to occupy on schedule.

Whether your project is in early planning or already mid-build, reach out now and we'll tell you exactly what the plumbing piece looks like.

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Frequently Asked Questions

Can an existing home's water heater serve an ADU?

Sometimes, but it depends on the water heater's capacity and the distance between the main home and the ADU. In many cases, a dedicated tankless water heater in the ADU is the more efficient and practical solution. Nolan will assess your setup and recommend the right approach.

How much does ADU plumbing cost in Portland?

ADU plumbing costs vary based on the size of the unit, whether a new water service connection is required, and the number of fixtures. PDX Plumber provides upfront pricing before any work starts. Call or book a free consultation to get a real number for your project.

Can PDX Plumber handle both rough-in and finish plumbing on an ADU?

Yes. PDX Plumber handles ADU plumbing from the very first rough-in through final fixture installation. Having one licensed plumber manage both phases reduces coordination headaches and keeps the project on schedule.

Does ADU plumbing require permits in Portland, OR?

Yes. Any new plumbing work in a Portland ADU requires a plumbing permit. PDX Plumber pulls all required permits and schedules inspections so your ADU gets a proper certificate of occupancy and is legal to rent or sell.

Do I need a separate water meter for a Portland ADU?

It depends on how the ADU will be used. Portland Water Bureau requires a separate meter and service lateral for ADUs that function as independent rental units in some cases. PDX Plumber can walk you through what your specific project requires and coordinate with the Water Bureau on your behalf.