One of the few joys of the current summer season on network TV has been the ''Charlie and Bill Show.'' The two new CBS Kuralt/Moyers back-to-back documentary series - which are actually titled On the Road With Charles Kuralt (8-8:30 p.m. Tuesdays)m and Our Times With Bill Moyers (8:30-9 p.m., Tuesdays)m - have proved to be a ratings surprise, so far ranking around 25th out of 67 in the overall standing. They've managed to hold their own against ABC's ''Happy Days'' and ''Three's Company,'' and cut into the ratings lead of one of TV's hottest new shows, ''The A Team'' (NBC). News documentaries traditionally finish in the final five.
The two shows airing tomorrow are especially fine examples of the kind of news coverage that has been sorely lacking in network nightly news shows. Kuralt , in his inimitably simple and straightforward way, meanders down America's back roads. He finds a man who sets up thousands of dominoes only to topple them, and he reminds us of the America that used to be by showing us old signs painted on brick walls.
Two other segments symbolic of what Charlie and America are all about concern a boatbuilding craftsman and a retired gardener. The boatbuilder, living far from the sea in Wisconsin, is a man concerned about doing things well rather than quickly. The retired gardener cultivated a gorgeous garden off an isolated highway, available to anybody who cared to stop and enjoy it. Kuralt himself stopped 11 years ago, as did a Korean woman during the program. She came back and helped the old man. Now, after the man's demise, Kuralt returns, too, to find this simple paradise now being maintained by the woman who stopped to admire beauty.
The Moyers show - ''The Lost Generation'' - is a thoughtful, poignant study of unemployment in Gadsden, Ala. But it is not merely a depressing look at poverty - it's a compassionate search for answers for a whole generation of ''laid-off Americans.''
Moyers accomplishes this by talking to people, probing their attitudes, revealing their disillusionment, not only in their employers and American consumers, but in the whole American dream.
An item in the news quoted by Bill in his summing up poses a challenge: ''Leaders of major corporations this weekend said they would rehire few of the workers they laid off during the recession, no matter how strongly the economy recovers. The executives said they see wrenching changes ahead for American workers.''
Soon, CBS News will have to make the big decision whether to allow the Tuesday ''Charlie and Bill'' double-header to expire when its scheduled run finishes in August. Both Charlie and Bill have indicated that they would like to continue despite heavy schedules, especially if the shows are given a hiatus for a few months so that the staff can gather material for the future.
CBS News, which is having a bit of an image problem with its many lawsuits, needs the shows as much as do American TV audiences. The regular on-air presence of these two is in great part responsible for the superb image that CBS News has managed to project in past days. News executives with short memories might also look back at the ''60 Minutes'' growth pattern to find a precedent for nurturing a potential blockbusting news show through its initial days.