A homeowner in Tacoma’s West End was building a detached accessory dwelling unit, a DADU, in the backyard, and it needed everything a house needs: its own water line, its own drains and a way to share the meter with the main house. Our crew handled the plumbing in stages through January and February 2026, starting at the street.
What We Did
In January Jerry dug down at the water meter and ran a 1 1/4-inch line up toward the house to a tee, with a 1-inch shutoff valve on each side: one for the main house and one for the DADU. From the tee he ran about 80 feet of new line out to the cottage, capped both ends and laid tracer wire along the trench so the buried line can be found later. The meter was due to be replaced, so the final connection waited, and a few days later Devin connected the new line at the meter and tied it into the main house’s 3/4-inch galvanized pipe in the crawl space.
In February, with the foundation poured, Jerry ran 3-inch ABS for the upstairs stack and the downstairs bathroom sink and out of the building, and a 2-inch line for the kitchen. He chipped the water line in through the foundation, then filled the waste system and tested it. Terrence came back to finish the groundwork, lowering the drains that needed to sit deeper and moving the 3-inch stack so the bathroom sink drain landed on the right side of the wall.
Why It Matters
- A DADU starts at the meter. The new water line, its size and where it splits decide how well both buildings get water, so that work comes before anything inside.
- Separate shutoffs save headaches. With a valve for each building, a repair in the cottage never means shutting off the main house.
- Tracer wire is cheap insurance. A buried plastic line cannot be found with a metal detector, and the wire makes it locatable for the next person who digs.
- Depth is settled before the slab. Terrence lowered the drains that needed to sit deeper and moved the stack while the ground was still open, which is far easier than fixing either through finished concrete.
Why the West End
The main house, like many older homes in the West End, still had 3/4-inch galvanized pipe in the crawl space, so the new line had to be joined to old steel with care. Tacoma now allows up to two accessory dwelling units on any legal lot, and backyard cottages like this one are going up across the city’s older neighborhoods. A detached unit needs its own water line and drain run out to it across the yard, which is why so much of this project happened outside rather than in the cottage.
Planning a DADU or an Addition
Call us or request service before the trench is dug, and we will walk the site, explain the water, drain and vent work and tell you what it will cost before any work starts.
More: rough-in plumbing for remodels, additions and ADUs · everything we do in Tacoma · pipe repair in Tacoma · water lines and main shutoffs
