2019 California Standards for Accessible Design Guide (effective January 1, 2020 with July 1, 2021 amendments)

11B-809.10.7.2 Location.

Water closets shall be located within bathrooms in a manner that permits a grab bar to be installed on at least one side of the fixture. The centerline of the water closet shall be 17 inches (432 mm) minimum to 18 inches (457 mm) maximum from a wall or partition that is 54 inches (1372 mm) minimum in length. In locations where water closets are adjacent to other walls, vanities, lavatories or bathtubs, the centerline of the fixture shall be 18 inches (457 mm) minimum from the obstacle.