If the works comprise, in connection with all or any of the amenities provided, the bringing of a piped supply of cold water into the dwelling for the first time there shall also be allowed an amount fixed, in the case of a standard grant, by the local authority and, in the case of a standard contribution, by the Minister.

The amount to be fixed under this paragraph shall be the amount which in the opinion of the local authority or Minister is one half of such part of the cost proper to be incurred in carrying out the works as is attributable to the bringing of the piped supply into the dwelling.