Two of the priciest surprises in an older Seattle house sit underground: the side sewer and an old heating oil tank. Neither shows up in listing photos, so I check for both before my buyers commit.
What is a side sewer, and who owns it?
A side sewer is the private pipe that carries wastewater from the house to the public sewer main. Seattle Public Utilities puts it plainly: you own your side sewer up to the public sewer pipe under the street. That means the owner's pipe usually runs under the yard, the sidewalk and part of the street. Some homes share a side sewer with a neighbor, and repairs then need both owners.
Why I scope every older Seattle house
Roots, cracked pipe and years of grease are the usual problems. SPU recommends a camera inspection when you buy a home, and every 8 to 10 years after that (every 2 to 3 years with big trees nearby). SPU lists video inspections at $230 to $845 depending on the pipe, and trenchless repair at $100 to $170 per foot. Most scopes my buyers order run $200 to $400. A scope during the inspection period turns an unknown into a number.
SDCI keeps side sewer records for many Seattle addresses, which can show the pipe's route and past work.
Buried heating oil tanks
Many older Seattle houses were once heated with oil, and some still have the tank in the yard. Seattle Fire Code requires a tank that has been out of service for a year or more to be decommissioned, in one of two ways:
Abandoned in place: the oil is removed, the tank is triple washed and filled with sand or foam, and the fill pipe is cut and capped.
Removed: the tank comes out of the ground and the hole is filled.
The work has to be done or supervised by a provider certified by the International Code Council as an underground storage tank decommissioner.
What to ask for
Sellers disclose an oil tank on Form 17, and buyers can ask for the paperwork: permit numbers, receipts, photos and the Seattle Fire Department's decommissioning certificate. No records? A tank sweep before you commit is cheap compared with a cleanup.
If a leak is suspected, it gets reported within 24 hours to 1-800-OILS-911. Washington's Pollution Liability Insurance Agency offers loans and grants for decommissioning and cleanup, and the Seattle Clean Heat Program offers rebates for switching to a heat pump.
Where this fits
These are two of the six Seattle checks in my buyer guide: what to check before you offer. For the rest of the inspection, see home inspections and pre-inspections.
Sources: Seattle Public Utilities, Taking Care of Your Sewer Pipe; City of Seattle, Oil Tank flyer.