(a) Grant assistance shall not be provided for a project unless the project is included in a complete waste treatment system and the principal purpose of both the project and the system is for the treatment of domestic wastewater of the entire community, area, region or district concerned.

(b) Allowable project costs do not include:

(1) Costs of interceptor or collector sewers constructed exclusively, or almost exclusively, to serve industrial users; or

(2) Costs for control or removal of pollutants in wastewater introduced into the treatment works by industrial users, unless the applicant is required to remove such pollutants introduced from nonindustrial users.