All measurements, tests and analyses of the characteristics of waters and wastes to which reference is made in Sections 1064.21 and 1064.24 shall be determined in accordance with “Standard Methods for the Examination of Water and Sewage,” published jointly by the American Public Health Association and the American Water Works Association, and shall be determined at the control manhole provided for in Section 1064.26 or upon suitable samples taken at such control manhole. If no special manhole has been required, the control manhole shall be considered to be the nearest downstream manhole in the public sewer to the point at which the building sewer is connected.