The Long Island Rail Road says it's taking action after video appeared to show murky water coming from the sink on board one of its trains.

The video, which surfaced Monday on Twitter, was taken on a Huntington-bound train that left Penn Station shortly before 1:30 p.m.

A LIRR spokesperson says it's unknown at this point what caused the discoloration but assures that it is not toilet water.

The railroad says it draws its water from municipal suppliers and those supply systems are being checked.

Mark Epstein, chairman of the LIRR Commuter Council, says the video points to a much bigger cleanliness problem that has plagued the LIRR for years.

"The issue of sanitary conditions on our trains, and on our platforms, and in our waiting rooms and even at Penn Station is of huge concern to the council," he says.

The LIRR says the train car from the video has been taken out of service and that crews are inspecting the yard where it was last worked on, in addition to examining water access points.

As a precaution, the LIRR says it is flushing out of all of its faucets, checking the water on every train car in the system and draining and refilling its supply tanks.