Cleaning up Lebanon's water

''It is said that only two things unite the Lebanese,'' says Muhammad Atallah , ''the legal tender and the sewage system.''

As president of Lebanon's five-year-old Council for Development and Reconstruction, his task is to build on that unity - a precious commodity in his strife-torn country.

But he thinks he has found a program that will appeal to all sides: a $4.7 billion nationwide waste management plan.

Such massive capital projects are ordinarily reserved for times of peace. But Dr. Atallah hopes to get this one under way without waiting for the fighting to end - because, he says, the need is so great.

World Health Organization (WHO) officials agree. They have documented the problem in photographs showing sewage outfalls on beaches, livestock grazing in dumps, and women washing carrots in drainage ditches.

If the plan materializes, says WHO engineer Mahmoud Suleiman, it will be ''the first of its kind attempted in any area by any agency.'' Although some other countries (such as Singapore) have national waste treatment systems, this is the first centralized program to build and coordinate wastewater management, stormwater drainage, and solid waste management.

The plan was developed under a tripartite agreement among the Lebanese Government, WHO, and the United Nations Development Program, and grew out of a recognition that pollution was threatening the health of the 5 million people in Lebanon.

Compounding the problem is the geology. The land is largely limestone, much of it cavernous. So the ground water is easily polluted. Nor are there any working municipal sewage treatment plants. Much of the waste is simply dumped into the Mediterranean along a coastline that was once filled with tourists.

To outsiders, however, the major problem appears less technical than political: the difficulty of rebuilding during the continuing strife, and the threat that any new construction might be destroyed by the fighting. The municipal treatment plant in Hammana, near Beirut, for example, was shelled in 1975 and has yet to be repaired.

But supporters of the plan say that the need for clean water transcends factional differences. They note that any new construction would need the de facto support of whichever group - Christian, Syrian, Palestinian, or others -- controlled the area in which it was built. But they claim that because all sides agree on the need, such support would be there.