Wash. Rev. Code § 80.28.070
Nothing in this chapter shall be taken to prohibit a gas company, electrical company, water company, or thermal energy company from establishing a sliding scale of charges, whereby a greater charge is made per unit for a lesser than a greater quantity for gas, electricity, water, or thermal energy, or any service rendered or to be rendered.
[ 2025 c 263 s 12; 1961 c 14 s 80.28.070. Prior: 1911 c 117 s 32; RRS s 10368.]