(1) Where a sanitary fitting is below the level of a public sewer, or is at a level which is not sufficient to secure a self-cleansing velocity of flow to such sewer, or where, in the opinion of the local authority, there is a risk of back-flow in the event of such sewer becoming surcharged, the sewage from such fitting shall be raised by ejector, pump, siphon or other approved mechanical appliance to such height as may be required by the local authority and discharged into such sewer, as and where, and at such maximum rate and at such times, as directed by the local authority.

(2) An efficient non-return-flow valve and a trap shall be fixed prior to connexion with such sewer, and shall be maintained in good working order.

(3) The waste-pipe or soil-pipe leading to such ejector, pump, siphon or other approved mechanical appliance shall be provided with a vent which, in the case of such soil-pipe, shall be not less than 100 millimetres in internal diameter, and in the case of such waste-pipe, shall be at least of the same internal diameter as such waste-pipe.