All municipal charges and bills shall be due and payable within
30 days of the date of notice of said charge or bill unless otherwise
specified in said notice of charge or bill. Interest shall accrue,
at the rate at which interest may be charged on tax bills under the
provisions of MGL c. 59, § 57, as amended, if any such charge
or bill remains unpaid after the expiration of 30 days from the date
of such charge or bill or such other specified payment.