The owner of a Brooklyn plumbing business and his wife and son pleaded guilty yesterday to charges related to schemes to drain millions of dollars from the Metropolitan Transportation Authority.

The defendants were Alex Figliolia Sr., 60, his wife, Janet Figliolia, 54, both of Holmdel, N.J., and their son, Alex Figliolia Jr., 31, of Staten Island. Their company, Alex Figliolia Contracting Corp., of Brooklyn, also pleaded guilty.

Figliolia Sr. and Jr. pleaded guilty to enterprise corruption, admitting that their criminal acts included bribing MTA officials and stealing and laundering MTA money.

State Supreme Court Justice Roger Hayes promised Figliolia Sr. a prison term of 1 3 /4 to 5 1 /4 years and Figliolia Jr. a term of 2 3 /4 to 8 1 /4 years. They would have faced up to 25 years in prison if convicted at trial.

Janet Figliolia pleaded guilty to second-degree bribery in exchange for a sentence of five years probation. She admitted paying bribes to an MTA official.

The plea deal also requires the Figliolias, who remained free on $1.5 million bail each pending January 5 sentencing, and their company to make joint restitution of $6 million. Prosecutors said the money will go to the MTA.

A 116-count indictment handed up in December alleged that the Figliolias, with the MTA employees’ help, stole money from the public agency by inflating invoices, overcharging for labor and materials, and forging business records. The defendants’ company charged $26 for a 49-cent connector tube and $250 for a $17.50 brass nipple, prosecutors said.

The schemes caused the MTA to pay Figliolia Contracting more than $18 million since 1994 for plumbing and renovation work at numerous MTA buildings, Manhattan District Attorney Robert Morgenthau said when he announced the defendants’ arrests.

Mr. Morgenthau said at that time no one was sure how much the Figliolias stole but it appeared to be in the millions of dollars.

During their plea statements yesterday, Figliolia Sr. and Jr. admitted the overcharges and inflated invoices and acknowledged stealing more than $1 million.

Mr. Morgenthau said the MTA defendants were Howard Weissman, 54, of East Meadow, N.Y., a former director of facility operations who earned $124,000 a year; Ronald Allan, 54, of Beacon, N.Y., a former $77,000-a-year facilities manager; and Gary Weissbard, 54, of Manhattan, a $71,000-ayear building manager.

Weissman pleaded guilty to enterprise corruption, Allan pleaded guilty to second-degree bribe receiving, and Weissbard pleaded guilty to receiving a reward for official misconduct, Mr. Morgenthau’s office said. None of them has been sentenced.

Weissman has not been promised a specific prison term, but part of his plea deal requires him to pay $100,000 restitution to the MTA. Allan will pay the MTA $20,000 and receive a sentence of one to three years in prison. Weissbard will pay restitution of $9,000 to the MTA and get five years probation.