The board of county commissioners of any county establishing a department of public works under this act is hereby authorized to provide public works service to political subdivisions located within the county, including without limitation water, sewer and cemetery districts. Such services shall be provided under written agreement with the governing body of such political subdivision and only under terms and conditions which will reimburse the county for the direct and indirect costs thereof. The amount charged for such public works services shall include a reasonable amount to cover the cost of general administration. Any moneys received by the county for the performance of public service functions under agreement with political subdivisions therein shall be considered as reimbursed expenses but receipts and expenditures for such services shall be budgeted for informational purposes.