THE FACT that the District government has wasted millions of dollars on supplies through a sloppy and decentralized procurement policy is no longer hot news. It has been known for quite some time. An investigation by this newspaper last year found that the city paid from 26 percent to 79 percent more than other Washington- area governments for a variety of common items, ranging from air filters for cars to shut-off valves for city plumbing. It has been reported that the city's current system has been so poorly coordinated that it wasted about $7 million a year on small purchase items alone. The District usually paid more than other jurisdictions when the sheer size of its procurement needs should have meant that it paid the lowest price.

The possible savings that could be gained, especially when Mayor Marion Barry talks so frequently about tight city budgets, seemed like an excellent fiscal goal. But Mr. Barry did nothing. He did nothing even though experts have talked about the savings that could be gained from a centralized procurement system since 1959.

Now the ball is in the D.C. Council's domain, and some positive steps are being taken. The council's Government Operations Committee, chaired by William Spaulding, voted 3-to-0 Thursday, as two other committee members walked out in protest, to revamp the city's contracting and purchasing policies by centralizing them under one authority.

Mr. Barry does not like the idea of centralizing procurement, largely because he thinks it infringes his power to delegate contracting authority. When a similar measure came up in Mr. Spaulding's committee last year, Mr. Barry was able to persuade Mr. Spaulding to withdraw the bill from consideration. Mr. Barry is exerting the same pressure this year, saying that he is awaiting the indings of an $80,000 study of the city's procurement system by the National Academy of Public Administration.

The system envisioned by the council committee would remove the privilege most District government department heads have to award millions of dollars in contracts on their own. It would place all such power under the authority of the Administrative Services Department. It would also lower the requirement for competitive bidding from purchases worth $10,000 to purchases worth $2,500. Mr. Spaulding suggests that this could save the city $20 million a year. It is an idea that deserves much further study, but it is also certainly preferable to the wasteful system that has been in effect.