Mass. Gen. Laws ch. 83, § 15A

Any city at any meeting of the proper municipal authority, or any town at a town meeting, may, from time to time, redetermine the uniform rate or uniform unit fixed under section 15, or under any special law, and charged to abutters for, or to the existing and potential sewer units to be served by, the construction of sewers, but this section shall not apply to the Massachusetts Water Resources Authority.