Edna Lauer has always been a little awed by the computers that print her bills, and so when she got her sewer and water statement in October, she checked every water outlet in her three-bedroom Adelphi home. She put a washer in a leaky basement spigot and replaced rubber valve in the toilet.

Still, she says, she never wastes water; her garbage disposal is broken and she uses her dishwasher only on Sundays. And though the Washington Suburban Sanitary Commission insists it is right Lauer cannot understand why she has been billed $556.74 for six months of water service - over seven times more than she has ever paid during the 25 years she has lived in her home.

See WSSC, B10, Col. 1

WSSC, From B1

Lauer says she has talked to everyone she can think of during the past month-neighbors, relatives, lawyers, a WSSC customer service representative-and all have told her, usually with a chuckle, that a silly mistake was made, that no one home could possibly use the 2,130 gallons of water a day that was charged to her.

But last week, the WSSC informed Lauer that a check had showed that her water meter was actually underestimating the water she consumed and that "an adjustment of past billings cannot be considered." Lauer is 66 and a widow, dependent on Social Security checks for income, and has had to ask her five children to raise $100 each to pay the bill. She no longer laughs at her predicament.

"I've just gone to pieces since I got this bill," she said yesterday. "I could never have used that much water, not if I left all the taps going 24 hours a day. It's crazy. But the water company doesn't believe me. With my luck, I'll have to pay it all."

What makes Lauer's bill particularly confusing is that a three-month WSSC "estimate" bill that she recieved in June Listed her water consumption at 24,000 gallons between March 28 and June 30, and charged her $42.60.

When the six-month bill came, new figures had appeared for those three months: 122,000 gallons and $250. Between June and October, the WSSC said, Lauer's water use continued at the same rate.

"We measured her consumption at the higher rate in June, but sent her a lower estimate while we checked her meter," said WSSC spokesman Art Brigham. "The meter showed she was registering low. So she will be charged the higher rate for that first three-month period."

But the water company, Brigham said, is willing to compromise with Lauer. A new meter has been installed at her property, and if the readings for the coming months return to the home's usual level of about 8,000 gallons a month, the WSSC will lower the charge for the last three months of the bill.

WSSC officials, Brigham said, still suspect Lauer is responsible. "She has a lot of people living in that house, and could have easily had a toilet leak that would have used up that much water," he said. "Of course, a leak of that magnitude would be very visible and audible, but-I don't want to speculate on the operation of the household."

"Their attitude is that we are cheating, that we fixed our meter or that we didn't notice a big leak, and we don't have the right to ask questions," said Lauer, who shares her home with her daughter, son-in-law, grand-daughter and a boarder. "But we're careful here, we aren't like that. They just don't want to admit that they are wrong."