Wash. Rev. Code § 63.18.010
In any lease or rental agreement for the lease of movable personal property for use primarily in this state (other than a lease under which the lessee is authorized to use such property at no charge), if the rental or other consideration paid or payable thereunder is at a rate which if computed on an annual basis would be six thousand dollars per year or less, no provision thereof purporting to disclaim any warranty of merchantability or fitness for particular purposes which may be implied by law shall be enforceable unless either (1) the disclaimer sets forth with particularity the qualities and characteristics which are not being warranted, or (2) the lessee is engaged in a public utility business or a public service business subject to regulation by the United States or this state.
RCW 63.18.010
Exclusion or modification of warranties: RCW 62A.2-316.