RCW 80.28.090: Unreasonable preference prohibited.

No gas company, electrical company, wastewater company, water company, or thermal energy company may make or grant any undue or unreasonable preference or advantage to any person, corporation, or locality, or to any particular description of service in any respect whatsoever, or subject any particular person, corporation or locality or any particular description of service to any undue or unreasonable prejudice or disadvantage in any respect whatsoever.