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
period.