RCW
7.28.070 and
7.28.080 shall not extend to lands or tenements owned by the United States or this state, nor to school lands, nor to lands held for any public purpose. Nor shall they extend to lands or tenements when there shall be an adverse title to such lands or tenements, and the holder of such adverse title is a person under eighteen years of age, or has been placed under a guardianship under RCW
11.130.265 or has been placed under a conservatorship under RCW
11.130.360. However, such persons as aforesaid shall commence an action to recover such lands or tenements so possessed as aforesaid, within three years after the several disabilities herein enumerated shall cease to exist, and shall prosecute such action to judgment, or in case of vacant and unoccupied land shall, within the time last aforesaid, pay to the person or persons who have paid the same for his or her betterments, and the taxes, with interest on said taxes at the legal rate per annum that have been paid on said vacant and unimproved land.