The other night, City Councilman T John Ray, one of the small school of politicians circling Mayor Barry in expectation of a kill, did one of those apres-pasta routines that are expected of candidates. Before a mildly interested crowd at a Georgetown house, he said why he was running for mayor, what he would do when he became mayor and why the present mayor should be sent packing. It was then that he mentioned the water bills.

And it was then that the crowd started to stir. Ray is either new at coffee klatches or not very adept at them so he did not seem to realize that he had stumbled on an applause line. At any rate, he kept on going and the crowd soon lost interest again, moving off gracefully towards the coffee and the sinfully rich fudge cake.

But those water bills are why Ray is in the race. And they are why he has been joined by his colleague on the council, John Wilson, and, it seems, by just about every politician of note Washington has to offer. The perception out there seems to be that Mayor Marion Barry is weak and the reason for that (either the perception or the reality) is those water bills.

The water bills, of course, are symbolic. They stand for a broken promise. Mayor Barry said he would make this city work. The opponent he ran against was not only Walter Washington, but a way of doing business -- an incompetence, a lethargy, a bureaucracy that functioned for its own sake. He was running against a water department that could not bill its customers and a board of elections that could not get through an election without something major going wrong.

He was running, in short, against this blame-the-computer-mentality. Washington seems to be the only city in the nation where computers do not work. Maybe there is something in the water or maybe the electrical current here is different than it is elsewhere. The real reason, though, is that the city government's computer is like the dog that ate the homework -- an excuse. Computers don't program themselves and they don't run themselves. People do that and people who know something about computers know the saying "garbage in, garbage out." Garbage is what we have been getting.

It just could be that Washington is no worse governed than other large cities. These things are hard to measure. And it just could be that the perception that it is is a reflection not of reality, but of racism -- a sort of they-can't-do- anything-right way of thinking. We all know who "they" are. It's also possible that in some ways the city is better run than it once was. It may be that the housing program is improved, that there is a better climate for business and that the summer jobs program is finally working.

But programs such as these take a long time to implement -- and even longer to evaluate. In the meantime, all people know is how the city government affects them. If it makes their lives miserable -- if, like a neighbor, they are dreading the arrival of a long-delayed and monster water bill -- they are not likely to be in a forgiving mood. John Lindsay went down the tubes in New York because he couldn't clear the snow in Queens County. Jane Byrne is mayor of Chicago today because her opponent also couldn't clear the snow and Richard Daley was mayor of that town for so long precisely because he could -- and did -- deliver city services.

The problem of deteriorating or nonexistent city services preceded Marion Barry and is likely to succeed him as well. It is a problem that seems impervious to energy or commitment on the part of the mayor -- two attributes that Barry seems to have. The water department is not in the mess it's in because Barry does not care, but because neither he nor anyone else seems to know what to do about it.

This is why the people who are either already running for mayor or threatening to run have an obligation to be more than just critical of the present mayor. They have an obligation to say how they would do better and to be as specific as possible. It would be nice to see plans and ideas and not hear cliches about how one man can make the difference. Maybe that's true, but that's what we heard the last time out. One man did make a difference.

Things got worse.