He hadn't received a water bill for a year and a half, and when one finally arrived, he was stunned. According to the D.C. water department, he owes more than $3,100. The man, who asked that his identity not be disclosed, has no idea how he's going to pay it.

"I don't want to come to their (the water registry's) attention again until I figure out what I'm going to do," he explained from his Northwest Washington home. "I have two children and a million other obligations. It wouldn't do me any good to go down there and try to work something out with them . . . I just don't have it.

"This is unbelievable . . . my home's in good shape, and there's no way I can owe this much. But I don't intend for them to put a lien on my house or shut the water off. I don't know what will happen."

When Eva Gray complained about her bills totaling nearly $3,000, the water department suggested her property might have had a leak. "I think they told the whole city that it's leaking," she stormed. A retired government worker, Gray got a bill for $774 for the period from April to November 1977, another for $1,347 for November 1977 through May 1978, and a third for $688.75 for the period from November 6, 1978, through April 29 of this year. The bills are all for a home in Northwest Washington which she and her husband rent as six apartments.

"It's inconsistent," Gray complained. "I would say a bill for $688 for 15 months or so is okay because it averages out to less than $50 per month. But $1,347 for six months? It doesn't make sense."

Gray has begun paying the current bill for $688, but intends to contest the other two.

"I have talked to the water people, I have written letters . . . they came out and found a leaking toilet. But it seems to me that every toilet in the District could leak and it wouldn't cost this much."

"If I hadn't been sitting down, I would have fainted," Nancy Horton said. The 76-year-old Northeast D.C. resident, a diabetic widow with a heart problem, recently received two water bills totaling $1,484. They are the first she has received since 1975 for a single-family home in Northeast which she rents to a middle-age couple. Her last bill, which covered a six-month period, was $45.92.

Like hundreds of other people who live in the District, Horton is confused and angry about her water bill, a bill she cannot afford to pay.

"The people who live in my home just can't use that much water," Horton, who lives with her widowed daughter, says. "They don't even have a washing machine, and the man is disabled."

During the five years she did not receive a bill Horton said she made regular visits to the water department to "beg" for a billing.

"All they would tell me is, 'You'll get a bill," she said.

The battle between District residents and the water department is an old one. There have been problems in the billing system dating back at least 10 years. Until recently, the entire process was done by hand, with meter readings entered in ledgers. The ledgers were often lost and records kept inaccurately. Large numbers of bills were sent in a single mailing, and payments often were not credited properly. The billing system now is automated, but fragments of former troubles remain.

The city recently stepped up efforts to collect delinquent bills, and in order to bring the system up-to-date, some customers are receiving bills for longer than the customary six-month period.

Although William F. Johnson, acting director of the Department of Environmental Services, said the longer billing period would be only 10 or 11 months in most cases, some customers -- the city would not say how many -- are receiving bills for a period of years.

"There may be some who are receiving these large bills," Johnson acknowledged, "but by and large, I believe people are only being billed for the 10- or 11-month period. And this (the 11-month bill) is a one-time thing. We will have the whole thing cleared up and be completely computerized by September."

At that point, Johnson said, residents can expect to be billed twice a year. (A check of major cities show that two to four times yearly is considered a common billing period for water services.)

Meanwhile, Johnson said, unusually large residential bills are being flagged by either the computer or a supervisor, and the customer is contacted. The property in question is then inspected for leaks or other plumbing problems and another reading taken. But none of the persons with extremely high water bills interviewed by The Washington Post had ever been contacted by the department. When a second reading or inspection was made, it always was initiated by the consumer.

"I don't know who's getting these outrageous bills you're talking about," Johnson said. "But someone like that . . . someone with a $2,000 or $3,000 bill for their residence, has an open invitation to come into my office so we can sit down and find out what the problem is."

"The problem," said one woman, interviewed just after she received an 18-month bill for $1,600, "is that these damn things are probably wrong in the first place. And in the second place, how on earth do they expect anyone to be able to pay this much money?"

Unlike some people who qualify for low-income utility-bill assistance, this woman, a federal clerk, said she will pay her bill "by feeding my kids hamburger and peanut butter for the rest of the summer and not taking a vacation." CAPTION: Pictures 1 and 2, Nancy Horton, 76, and her water bill; Picture 3, Meter reader lifts lid to take meter reading.; Picture 4, Nelson Terry says he won't pay $846 bill.