Each and every connection of the water mains installed by said County Commissioners with said water mains of the Mayor and City Council of Baltimore shall be at the expense of said County Commissioners and under the supervision of the Water Engineer of Baltimore City or such other person or persons as the Water Engineer of Baltimore City, the Water Board of said City may appoint or such other body or officials as may for the time being have charge of the water system of said City, and said County Commissioners to bear the expense of said supervision. Every connection shall include a meter of a make and design approved by the Water Engineer of said City, to the end that all water flowing into each and every water system constructed by said County Commissioners may be measured, and said County Commissioners shall pay the said Mayor and City Council the actual cost of delivering said water at the points of connection and meter, with five per cent added, and the actual cost of purifying said water, with five per cent added, the cost of delivering and of purification to be determined by the Public Service Commission of Maryland and to be subject to review and revision by the said Public Service Commission once only in every five years on application of the County Commissioners of Baltimore County or the Mayor and City Council of Baltimore. In determining cost of delivering and of purification, the value or cost of impounding water at any source of supply and the value of cost of pipe lines and filtration plants shall be disregarded, it being the intention hereof that the sales price of water by the Mayor and City Council of Baltimore to the County Commissioners of Baltimore County through the connections and meters aforesaid shall be the cost of pumping the water to the points of connection and meter, and the cost of purifying such water, and in addition, a sum equal to five per centum of said cost of pumping and purification, without any allowance for interest on investment or for amortization. P.L.L., 1927, §908 1938, §1188 1949. §784 1969, §25-23 1922, ch. 289