Dozens of firefighters battled for several hours to bring a blaze under control at a former water treatment works.
Plumes of black smoke billowed from the plant on Smithies Lane, Heckmondwike, and could be seen for miles around.
Crews from several fire stations including Illingworth and Odsal were called to the scene from 7 pm last night (Wed).
The fire service said the blaze was caused by a large amount of plastic which had caught fire.
The blaze centred on a circular filtration system and is still being investigated.
A West Yorkshire Fire Service spokesman said it had received a large amount of 999 calls from people who had seen the smoke.
The surrounding area was badly affected by smoke although the skies had cleared by around 8.30pm.