One of the nation's largest manufacturers of water coolers has agreed to replace older models that release excessive amounts of lead in drinking water, the Consumer Product Safety Commission announced yesterday.

The agreement by Halsey Taylor Division of Scotsman Group covers coolers produced before April 1979, many of which have tanks lined with lead. Hundreds of thousands of coolers made prior to 1979 are still used in public and private schools, recreational centers and office buildings, but officials do not know how many pose health risks.

Halsey Taylor's action follows an Environmental Protection Agency survey of coolers that detected lead levels as high as 2,000 parts per billion -- 200 times the standard -- with an average of several hundred ppb, according to officials.

Once considered a threat limited to smelter workers and children who eat paint chips, lead is now regarded as one of the most pervasive and dangerous environmental poisons.

Even at low concentrations in the blood, it is known to retard development of children, complicate pregnancies and cause high blood pressure in men.

The phasedown of leaded gasoline has dramatically cut airborne levels of the toxic metal, leaving drinking water as a primary source of exposure.

After the EPA detected excessive lead levels in tap water in millions of households, the Navy decided to test for the pollutant in its buildings.

The survey focused on water coolers as a problem, prompting Congress in 1988 to order an inventory by the EPA of potentially dangerous coolers and action by the CPSC to remove them.

"Cooler owners and people drinking from the coolers, especially children in schools, day care, religious and recreational centers, will benefit," CPSC Chairman Jacqueline Jones-Smith said of yesterday's agreement with Halsey Taylor.

A spokesman for Halsey Taylor said a small portion of the coolers made before 1979 are still in service and that most do not contribute to excessive lead levels.

Under its agreement with the CPSC, Halsey Taylor will replace the coolers or refund their cost if they are older than 11 years and their water has been found by tests to contain more than 20 parts per billion of lead.

The current standard for lead in drinking water is 50 ppb, but the EPA has proposed cutting it to 10 ppb.

The Illinois-based firm pledged to detail its offer in notices over the next three weeks to schools, day care centers and headquarters of the YMCA and YWCA.

No other brand of cooler has been found to have a lead liner, according to the EPA. But other brands have produced excessive pollution levels because of lead solder, officials said.