"Additive" means a commercial product intended to affect the performance or aesthetics of an on-site sewage disposal system.

"Additive manufacturer" means any person who manufactures, formulates, blends, packages, or repackages an additive product for sale, use, or distribution within Washington state.

"Approved" means a written statement of acceptability, in terms of the requirements of this chapter, issued by the Washington state department of health.

"Chemical additive" means those additives containing acids, bases, or other chemicals deemed unsafe by the department for use in an on-site sewage disposal system. Chemicals identified as unsafe are specified in WAC 246-273-050.

"Department" means the Washington State Department of Health, P.O. Box 47826, Olympia, Washington 98504-7826.

"Failure" means:

• Effluent has been discharged on the surface of the ground prior to approved treatment; or

• Effluent has percolated to the surface of the ground; or

• Effluent has contaminated or threatens to contaminate a groundwater supply.

"On-site sewage disposal system" means any system of piping, treatment devices, or other facilities that convey, store, treat, or dispose of sewage on the property where it originates or on nearby property under the control of the user where the system is not connected to a public sewer system. For purposes of this chapter, an on-site sewage disposal system does not include indoor plumbing and associated fixtures.

"Person" means any individual, corporation, company, association, society, firm, partnership, joint stock company, or any governmental agency, or the authorized agents of any such entities.

"Sewage" means any urine, feces, and the water carrying human wastes, including kitchen, bath, and laundry wastes from residences, buildings, industrial establishments or other places.