GLEN HEAD - Hundreds of North Shore homeowners got an unwelcome surprise when they opened their water bills.

Glen Head resident Jillian O'Day says her last quarterly water bill was $910 for a three-month period. Back in April, she says she got a $590 bill.

O'Day says her water use is the same as in the past when she paid much less.

New York American Water says customers' bills were high in April because they had been undercharged for most of 2012. The company says it got state approval to recoup the lost money with the April bill.

The water company says it's looking into why O'Day's latest bill is so high. New York American Water says customers with abnormally high bills should call customer service immediately.

Glen Head residents, including O'Day, have filed complaints with the Public Service Commission and the Attorney General's Office. They are still waiting for a response.