RCW 70A.125.200: Fire sprinkler systems—Shutting off—Liability.

(1) A person or purveyor that owns, operates, or maintains a public water system shall not be liable for damages resulting from shutting off water to a residential home with an installed fire sprinkler system if the shut off is due to: (a) Routine maintenance or construction; (b) nonpayment by the customer; or (c) a water system emergency.

(2) Any governmental or municipal corporation, including but not limited to special districts, shall be deemed to be exercising a governmental function when it acts or undertakes to supply water, within or without its corporate limits, to a residential home with an installed fire sprinkler system.