Bailey, a center, drew the Americans even at 5-5 on an extra-man goal with 5:58 left in the third quarter and he put the U.S. ahead for good at 6-5 on another power-play score with 1:56 remaining in the third.
He netted his third goal with 50 seconds left in the fourth period to give Team USA what then was a three-goal cushion.
Peter Varellas also scored three goals for the U.S. and Adam Wright added two. Cosmin Radu led Romania with a game-high four goals.
The U.S. next faces Great Britain Thursday at 10:20 a.m. PT. The Americans and Serbia are currently tied atop Group B with 2-0 records and will face each other Saturday at 11:40 a.m. Team USA will close out group play Monday against Hungary at 7:30 a.m.
"We are on track," Bailey told reporters afterward. "Two wins is as good as it can get."
Bailey, a four-time All-American at UCI and 1998 Mountain Pacific Sports Federation Player of the Year, is one of the first two male athletes (along with Tony Azevedo) in USA water polo history to compete in four Olympics. UCI alum Jeff Powers is making his third appearance in the Olympics and Tim Hutten his second. They were members of the 2008 American squad that won silver in Beijing.
In Tuesday's win over Romania, Powers had three shot attempts in 18 minutes of action and Hutten one shot in six-plus minutes.
John Mann, a Corona del Mar High product, scored once for the Americans on Tuesday.
— From staff reports
WOMEN'S BEACH VOLLEYBALL
Misty May-Treanorannounced last week that the London Olympics would be her final competitive tournament, as she will retire from the sport to concentrate on family and other pursuits.
May-Treanor, 35, a former Newport Harbor High standout who grew up in Costa Mesa, and her partner Kerri Walsh Jennings, 33, are attempting to win a third gold medal in beach volleyball in London. The duo have long been the dominant team in the history of the sport, but May-Treanor has said she will not play again after London.
Walsh Jennings has said she will continue playing, but will have to find a new partner.
The online beach volleyball database lists May-Treanor with 111 tournament victories, both domestic and international, during a professional career that began in 1999. Her career winnings are listed at $2,132,733.
She was Most Valuable Player on the Assn. of Volleyball Professionals tour four times (2005-2008) and earned the same honor internationally from Federation International de Volleyball in 2005 and 2008.
She was NCAA Athlete of the Year in 1998 at Long Beach State, where she led the 49ers to a pair of national championships.
— From staff reports