Wash. Rev. Code § 86.09.514
The matter recited in the certificate of sale must be recited in the deed, and such deed duly acknowledged or proved is prima facie evidence that:
First. The property was assessed as required by law.
Second. The property was equalized as required by law.
Third. That the assessments were levied in accordance with law.
Fourth. The assessments were not paid.
Fifth. At a proper time and place the property was sold as prescribed by law and by the proper officers.
Sixth. The property was not redeemed.
Seventh. The person who executed the deed was the proper officer.
Such deed, duly acknowledged or proved, is (except as against actual fraud) conclusive evidence of the regularity of all the proceedings from the assessments by the secretary, inclusive, up to the execution of the deed. The deed conveys to the grantee the absolute title to the lands described therein, free from all incumbrances except the lien of outstanding general ad valorem taxes and of unmatured special assessments. When title to the land is in the United States or this state, such deed shall be prima facie evidence of the right of possession.
RCW 86.09.514