For almost a decade the City of Chesapeake, a sprawling, marshy land mass on the North Carolina border, has attempted to wean its citizens from well water.

And for years, at least 270 well owners have balked. Some claim that the city water here is tainted with asbestos fibers because the pipes used to carry the water contain asbestos, a material commonly used in such pipes. Ignoring the demands of City Hall, they have insisted on drinking their own.

"It bothers me no end to have someone from the city water department drive out to my house in a little truck and tell me that I can't drink my own water!" says Carl Cahill, a leader of the protest. "I'm fighting for freedom of choice, and for my kids' health. City water is bad for you."

So it went, until this fall, when Chesapeake declared war on Cahill and his followers.

For Chesapeake, a community of 116,000 anxious to prove it is more than an urban annex to the Dismal Swamp (which it shares with North Carolina), there is more at stake in the dispute than tap water.

The feud is testing the identity of a city created only 18 years ago when the tiny city of South Norfolk merged with rural Norfolk County. At 353 square miles, the resulting city was--and is--only 12 square miles smaller than New York City.

Chesapeake, 13th largest city in the United States in terms of area, is so spread out and sparsely developed that its first passenger elevator was installed only seven years ago. Many of the city's main thoroughfares are deserted two-lane highways that stretch beyond newer suburban communities into vast farmlands veined with dark, slow-moving streams. City residents say 18 years has not entirely erased distrust between distant boroughs.

"There is residual provincialism," acknowledges Belton E. Jennings III, executive vice president of the Chesapeake Chamber of Commerce. "You're talking about people whose idea of Civil Defense is to circle the wagons."

"A clash of cultures," is how Vice Mayor Willa Bazemore describes it.

Faced with a $1.5 million operating deficit on its new water and sewage treatment plants, Chesapeake recently delivered an ultimatium to the well owners: Hook up or face fines of $1,000 and up to a year in jail.

The city has served criminal summonses to 12 longstanding violators of a city law banning use of well water where city water is available. George Pipkin, the city's water bill collector, has begun referring to himself as "Snidely Whiplash" and two outraged well owners have sued to block the mandatory hookups, promising a fight to the bitter, waterlogged finish.

Cahill, a newspaper reporter turned free-lance publicist, argues that the city water is contaminated with asbestos fibers from the asbestos-cement water pipes and that the city has no constitutional right to tell him he can't drink his well water.

Brandishing Environmental Protection Agency statistics like pistols, Cahill has made the issue his cause. In his eight-year fight with Chesapeake, he has been to court at least five times and has become as well-known and welcome a sight to city officials as crabgrass. He has hired lawyers, borrowed on his insurance, filled two closets in his home with documents and managed to raise significant doubt in the minds of other well owners over whether they should ever hook up.

Cahill's unsuccessful appeals of lower court decisions against him have gone as far as the Supreme Court.

Government researchers studying the effects of ingested asbestos on rats and hamsters say, however, that there is no conclusive evidence yet that asbestos in drinking water is a carcinogen. EPA tests of Chesapeake drinking water have turned up what investigators termed "non-significant" levels of asbestos in the drinking water.

Cahill and others aren't buying. They point out that for years inhalation of asbestos by industrial workers was regarded as harmless, but is now believed to cause a rare and deadly cancer.

"The government says there is no risk of cancer from asbestos in drinking water," says Sidney Preedy, an aluminum company employe and lifelong Chesapeake resident who is suing the city. "But we know that breathing the stuff is bad for you. So what happens if you run asbestos-contaminated water through a vaporizer? Then what? The answer is, nobody knows."

City officials and asbestos-cement pipe manufacturers have maintained steadfastly that the pipes are safe. In 1978, the Chesapeake City Council voted to stop further installation of the pipe, at the recommendation of a citizen study committee. Though the group could find no reason to remove the pipe already installed, it advised that "prudence" called for a moratorium.

Fear of asbestos is not everyone's motive for the fight. Many well owners, as well as others cheering from the sidelines, resent being forced to pay for what they regard as an expensive water treatment system that often produces unpalatable water. With the droughts that have plagued the Tidewater, they say, Chesapeake should be begging people to use well water.

"We've got the highest water rates in Tidewater," fumes A. M. Stevens, a Norfolk resident who has run Chesapeake's 60-plane South Norfolk airport since 1949. " . . . There's only one thing this city is worried about--that's getting the money to pay for that water system. Chesapeake? Hell. If I lived here, I'd move."

Most city officials are confident that they will be able to convince holdouts to hook up. Cahill and his supporters scoff at that. "It's the principle of the thing that I'm fighting for," says Cahill. "And I've got lots of time."