A federal contractor says he will be suing the U.S. Department of Energy for $40 in water charges because the federal government still has not paid for the water heater.

In a lawsuit filed Friday in the U, the contractor, James B. Johnson of St. Louis, Missouri, is seeking $40 million in water utility charges for the 2010-11 water heater system he said he built in his home.

The suit is a response to the Energy Department’s December 2015 decision to give the contractor $12.5 million to retrofit the heating system to meet new standards.

The agency said the retrofit would have made the system fully compliant with federal standards.

A spokeswoman for the Energy department said the agency had no comment on the lawsuit.