(1) Whenever, in the opinion of the local authority, an adequate water-supply is available, every residential, institutional, business and public building shall be provided with a plumbing system and sanitary fittings discharging into-

a) a public sewer (if available); or

b) if a public sewer is not available, into a septic tank or a conserving-tank or other approved means of sewerage-disposal.

(2) Subject to the provisions of subsections(3) and (4), the sewerage system of any premises shall be separate and distinct from the sewerage system of every other premises.

(3) In the case of any group or block of buildings, a combined private sewer may be permitted, subject to the approval of the local authority.

(4) In any case referred to in subsection (3), the local authority shall have the right to carry out all, or any portion of, the work, and to recover the cost of construction from the various owners, apportioned by the local authority, in such a manner as it may deem to be just.