One of the Seattle area's free RV dump stations is found at the Smokey Point Rest Area, which is 45 miles north of Seattle in Arlington. Another place at which you can empty your tanks for free is the Silver Lake Rest Area, which is just 23 miles north of Seattle in Everett. You could also take advantage of the free dump station at Marysville Planning and Public Works Building, which is located in Marysville 34 miles north of Seattle. Yet another free option is the Budd Inlet Treatment Plant, which is 60 miles southwest of Seattle in Olympia. A final option is the SeaTac Rest Area, which is located in Federal Way 25 miles south of Seattle.

In Seattle itself, you can clean out your tanks at Evergreen RV Supply all year round for a mere $3 per use. Should you choose to camp at Lake Pleasant RV Park, then you'll be able to use their dump station for free. Issaquah Village RV Park's dump station is also free for paying customers, but they also allow the public to utilize it for $10 a use.