When you're buying a home in Seattle, especially a newer one, you may come across something called a sewer capacity charge on the property disclosure. It's not complicated, but it catches buyers off guard if they've never seen it before. Here's what it is, how it works, and what to do about it.

What Is the Sewer Capacity Charge?

King County has charged a sewer capacity charge on properties with new connections to the sanitary sewer system since 1990. The charge is meant to help pay for the regional infrastructure: treatment plants, pipes, and wastewater facilities that serve the county's growing population.

When a property connects to the sewer system for the first time, the capacity charge begins. It runs for 15 years, billed monthly, and the rate is set annually by the King County Council. The 2026 rate is $77.99 per month for a standard residential property.

The charge belongs to whoever owns the property. It is not tied to the original owner who triggered it. If a property is sold before the 15 years are up, the remaining balance transfers to the new owner at closing.

When Does It Come Up in a Purchase?

If you're buying a newer home or one that was recently connected to the sewer system, there's a good chance a capacity charge is still running. Sellers are required to disclose it, and it will appear in the property disclosure documents.

It also comes up on properties that were converted from a septic system to city sewer relatively recently. That's less common but worth knowing.

Older homes that have been connected to the sewer system for more than 15 years won't have a remaining balance. The charge has been paid off, either through monthly payments over time or a lump sum payoff.

How Much Is Left and Does It Matter?

The math is simple. If a home is three years into the 15-year charge, there are 12 years remaining. At $77.99 per month, that's roughly $11,200 remaining on the balance. On a home that's 10 years in, you're looking at around $4,700 remaining.

The remaining balance simply becomes part of your monthly utility costs until the 15 years are complete. It's a known, fixed amount that's easy to account for once you know it's there.

Can You Negotiate It?

Yes, and it comes up in purchase contract negotiations regularly. A buyer can request that the seller pay off the remaining balance before or at closing. Whether the seller agrees depends on how much is left and how motivated they are.

On a home that's only a few years old with most of the 15-year period remaining, sellers are generally reluctant to pay off a large balance. On a home that's 12 or 13 years in with only a small amount remaining, it's a much easier ask and sellers will often agree.

One thing worth knowing: the remaining balance can be paid off at any time during the 15-year period at a discounted lump sum amount. That option is available to both sellers and buyers.

The escrow company handling your closing will pro-rate the charge appropriately between buyer and seller based on the closing date if you're assuming it rather than requiring a payoff.

The Bottom Line

The sewer capacity charge is not a deal breaker and it's not a hidden trap. It's a disclosed, quantifiable cost that can be negotiated or absorbed depending on your situation. The key is knowing it exists before you're deep into a transaction so you can factor it into your offer strategy from the start.

If you're buying a home in Seattle and want to make sure you're accounting for all the costs and considerations specific to this market, reach out at KimReidy.com.