12. Any dispute between a water undertaker and a person who has installed or proposes to install a water fitting—
(a)as to whether the water undertaker has unreasonably withheld consent, or attached unreasonable conditions, under regulation 5; or
(b)as to whether the water undertaker has unreasonably refused to apply to the Department for a relaxation of the requirements of these Regulations,
shall be referred to arbitration by a single arbitrator to be appointed by agreement between the parties or, in default of agreement, by the Department.