Pennsylvania American Water Co. says a boil-water advisory affecting 12,600 Bucks County customers will remain in effect until at least Tuesday, but Pennsbury schools served by the water company plan to reopen Monday.

The water company said that customers in Yardley Borough, Lower Makefield Township, and parts of  Falls Township served by a treatment plant that experienced mechanical problems Thursday night should continue to boil water before drinking it.

State environmental regulators allowed Pennsylvania American to begin testing water samples on Sunday evening to establish the water's purity, but regulations require two consecutive days of test results with no signs of bacteria before the advisory can be lifted.

The Pennsbury School District, which suspended classes Friday as a precaution at all 15 of its properties, announced Sunday that classes will resume Monday at all its schools. Pennsylvania American will supply pallets of bottled water for students and employees at the eight schools it serves, the district said.

The schools that will receive bottled water are Afton, Eleanor Roosevelt, Edgewood, Makefield and Quarry Hill Elementary Schools, as well as Charles Boehm, Pennwood and William Penn Middle Schools.

Pennsylvania American has stabilized the treatment plant in Lower Makefield and "is continuing to analyze the plant operations to ensure there is not a repeat of the mechanical control issues that caused the increased turbidity level last Thursday," spokesman Terry Maenza said in a statement. Turbidity, or cloudiness, could be an indication of the presence of bacteria, viruses, or parasites that can cause nausea, diarrhea, or headaches, the company has said.

Water tankers are available for customers — who are urged to bring their own containers — from 6 a.m. to 10 p.m. at Yardley-Makefield Fire Company locations, Gas Light Village, Big Oak Shopping Center, and Village Market in Lower Makefield.