Standard pressure

(1) Each utility shall, subject to the approval of the commission, adopt and maintain a standard pressure in its distribution system at locations to be designated as the point or points of "standard pressure." At one such point a recording pressure gauge shall be maintained in continuous service. (2) Under normal conditions of use of water the pressure at a customer's service connection shall be not less than 25 p.s.i.g. and not more than 125 p.s.i.g. (3) Pressure outside the limits specified will not be considered a violation when the variations arise from: (A) The action of the elements; (B) infrequent fluctuations not exceeding five minutes duration; (C) service interruptions; (D) causes beyond the control of the utility; (E) service elevations. (4) At regular intervals, each utility shall make a survey of sufficient magnitude of pressures in its distribution system to indicate the quality of service being rendered at representative points on its system. Such surveys shall be made during periods of high usage at or near the maximum usage during the year. The pressure charts for these surveys shall show the date and time of beginning and end of the test and the location at which the test was made. Records of these pressure surveys shall be maintained for a period of six years at the utility's principal office in the state and shall be made available to the commission upon request.