(Adds detail on water tests)
By Edward McAllister
NEW YORK, Feb 18 (Reuters) - Tank cars from a derailed oil train were still on fire in West Virginia on Wednesday, two days after an explosive accident in which 25 cars went off the rails, a CSX Corp spokeswoman said.
Twenty cars caught fire after Monday's derailment in the small town of Mount Carbon 33 miles (54 km) southeast of Charleston.
"We still have some fires on and near tank cars," CSX railroad spokeswoman Melanie Cost said, without giving an exact number. The burning cars were being left to burn out, and some cars were still leaking oil.
The fires destroyed a house and prompted the evacuation of two nearby towns. No serious injuries were reported.
More than 100 people remained evacuated from their homes on Wednesday, Cost said.
Booms were deployed in the nearby Kanawha River to collect any leaking oil but none was detected in water tests carried out by local water provider West Virginia American Water. The company said in a statement that it restored water service to all customers in the area after closing a nearby water treatment plant following Monday's accident. Hourly water samples will be conducted while the clean up continues, it said.
The Federal Railroad Administration was investigating factors that may have played a part in the accident, including track conditions, the train's speed before it derailed and the weather, according to CSX.
When workers can approach the scene, CSX hopes to begin putting some of the tank cars that were not burned back on the rails.
All the tank cars on the 109-car train were newer models built after 2011 know as CPC 1232, the railroad said, and not the older DOT-111 cars that have been criticized for being prone to puncture in accidents.
(Reporting By Edward McAllister; Editing by Jonathan Oatis and Andrew Hay)