D.C. City Council member H.R. Crawford (D-Ward 7) said yesterday that he had been advised that his sponsorship of a bill to reduce water and sewer charges of nonprofit housing projects does not constitute a conflict of interest, although his private firm manages six projects that would directly benefit.

Crawford released a copy of an opinion written by Lawrence H. Mirel, general counsel to the City Council, which concludes that "there is no conflict of interest," provided the bill applies solely to federally subsidized nonprofit housing in which Crawford has no financial interest.

Mirel's opinion, dated Nov. 16, 1981, said that Crawford's firm, Crawford/Edgewood Managers Inc., could not benefit from the bill since management fees, which are set by the federal government, are based on a percentage of gross rent collections.

"If projects costs (including water bills) are reduced, rents will be reduced -- or at least will not be increased," Mirel said. "Since management fees for the nonprofits are based on a percentage of gross collections, a reduction in water and sewer rates would not increase the management fee, but may have the effect of reducing it."

Crawford's bill, which is before the council's Finance and Revenue Committee, was designed to further subsidize housing projects for low-income families by reducing their water bills by 50 percent.

The bill also would authorize the mayor to excuse housing projects that experience severe financial problems from paying back water bills.

The measure would cost the city between $800,000 and $900,000 annually, according to an official of the D.C. Department of Environmental Services. The proposal was backed "in concept" yesterday by Council member John A. Wilson (D-Ward 2), chairman of the finance committee.