WHEN THE NATIONAL Conference of Black Mayors called a special meeting not long ago in Atlanta, the issue before its member was clean water. The mayors, particularly those from the rural areas, were worried that some of the federal assistance to small towns in need of safe drinking water and sewer facilities was in jeopardy.

The mayors' worry is anything but idle. At the moment, the future of the National Demonstration Water Project is being debated by the Community Services Administration (which has provided money for the program since 1972), the Office of Intergovernmental Affairs in the White House and a coalition in Congress. The debate, it needs to be emphasized, is not about the record or the value of NDWP. Officials at CSA have praised it as "clearly a good program." The White House agrees. As for Congress, its supporters range from Sen. James B. Allen (D-Ala.) to Sen. George McGovern (D-S.D.). As Sen. Allen describes it: "NDWP was probably the first national program to see the great potential for rural water and sewer development that exists in the nation's network of rural electric cooperatives . . . I find this method to be a sensible and cost-effective way to deal with a problem that is an important one in my state and in many other states with large rural populations."

Having done so well over the years - in providing technical assistance to local communities, in working with small town mayors and citizens - NDWP now finds that success has its problems, too. Several months ago, it asked CSA for $5.2 million for another 12 months of operation. That was too much, the agency said, citing its budget constraints. NDWP compromised and came back with a $2.5 million request for eight months. That was still too much. At this point, officials in the White House's Intergovernmental Affairs Office stepped in to seek a way to bring the two sides together. NDWP finally agreed on a bare-bones figure of $1.5 million.

That was in mid-March, and it is where things stand now. The delay is unfortunate, particularly because this is a program that even CSA praises. Agency officials now say that the final details are being worked out. That is a positive sign. Eventually, however, the agency and the White House are going to have to locate a new home for NDWP. The function of CSA is not to keep on funding demonstration projects, however, well they have done. In this case, according to White House officials, NDWP should be spun off to one or another of the five federal agencies that deal with rural water and sewer problems.But the current regulations of these agencies are not flexible enough to let them absorb NDWP.

It isn't as though the administration has so many successful poverty programs that it can stand aloof when one of the good ones need help. Nor is it as though rural towns have no severe water problems.According to NDWP, 3.6 million citizens - most in rural areas - live in houses with no running water. In addition, nearly 10 million citizens live in houses that lack complete plumbing. With such an obvious need, the administration has an opportunity to make a commitment to a project that has proven itself, both here in Washington and in the field.