RCW 80.28.170

If any consumer to whom a meter has been furnished shall request the commission in writing to inspect such meter, the commission shall have the same inspected and tested, and if the same, on being so tested, shall be found to be more than four percent if an electric meter, more than two percent if a gas meter, more than two percent if a water meter, or more than two percent if a thermal energy meter, defective or incorrect to the prejudice of the consumer, the expense of such inspection and test shall be borne by the gas company, electrical company, water company, or thermal energy company, and if the same, on being so tested shall be found to be correct within the limits of error prescribed by the provisions of this section, the expense of such inspection and test shall be borne by the consumer.