King County Wastewater Treatment Division, Industrial Waste Program

Industrial Waste Discharge Permit / Authorization

A business that sends process wastewater from manufacturing, remediation, cleaning or rinsing to the King County metropolitan sewer needs discharge approval from the King County Industrial Waste Program, regardless of whether it sits inside a city or in the unincorporated area, wherever that city's sewer flows to the county system. Issuance fees range from $1,500 (letter of authorization, new) through $2,000 (minor discharge authorization) and $3,000 (major) to $6,000-$12,000 for a discharge permit, with lower renewal and revision fees; approvals last up to five years. Regulated facilities also pay an annual compliance monitoring fee by tier and, for high-strength food and beverage wastewater, a surcharge of $0.4890 per pound of BOD and $0.5675 per pound of suspended solids (2026). No King County code section calls ordinary restaurant kitchen and restroom discharge an automatic exemption: KCC §28.82.260 defines a 'domestic user' only as one contributing wastewater from a residential dwelling unit, so a business is never itself a domestic user, and §28.82.380 defines industrial waste to include waste from commercial food processing and other business processes. Whether a specific restaurant's or auto shop's discharge crosses into industrial waste — as opposed to ordinary sanitary use that needs no authorization — is a judgment KCIW makes case by case; call 206-477-5300 rather than assuming either answer. Non-categorical dischargers must apply at least 60 days before discharge begins, and federal categorical dischargers at least 90 days before.