If a portion of the water furnished to any premises is not directly or indirectly discharged into the sewerage system, the quantity of the water shall be deducted in computing the sewerage service charge or rental; provided, a separate meter shall be installed and operated to register the quantity so not discharged into the sewerage system; provided, also, that, where it is not practicable to meter the portion of the water not discharged into the sewerage system, the adjustment may be made as shall be fair and equitable in order to determine the amount of the service charge or rental; but until the adjustment shall be effected that water consumption basis hereinbefore prescribed shall remain in full force and effect.
(Prior Code, § 3.20)