Section 120-H. Further provisions as to apportionment of cost

Each of the
  contracting  municipalities  or  districts  shall  pay  its   just   and
  proportionate  share  for  the public improvement authorized by this act
  and the general laws, including its just and proportionate share of  the
  cost  for  the removal of sewage and of maintenance and carrying charges
  of the system. The manner of arriving at the share each local government
  shall bear and the method of payment  thereof  as  hereinafter  provided
  shall be determined by its local board or commissioners having charge of
  sewage,  before  such  contract for construction or for sewerage removal
  becomes effective, as hereinafter provided.