(5) If a drain or related service connection or part thereof is found on investigation by a water services authority to be inadequate, defective, foul or neglected or to permit infiltration or exfiltration of water or waste water, and it appears to the water services authority that after executing the necessary remedial works, any premises would still not be drained satisfactorily, such water services authority may serve on the owner of such premises a notice under section 42, or may provide or contribute to the cost of providing drainage for the premises.".