Investigators are looking into the cause of the fire. Photo: Supplied / Kevin Patterson
*This story has been updated to reflect the council's clarification that the burnt MDF board does not contain arsenic.
Tasman District Council is confident no contamination has entered a nearby river and estuary after a large fire in a building supplies store.
Emergency services were called to the fire just before 3am on Thursday at the ITM retail outlet in Tākaka.
The blaze was "well-involved" when firefighters arrived in 13 trucks and one support vehicle. The fire was contained within two hours.
Photo: Supplied / Kevin Patterson
Earlier, Tasman District Council advised those who used water from the Motupipi River from a tributary near Motupipi Street to stop taking it immediately, while they assessed possible contamination from potentially harmful chemicals that burned and mixed with the water.
"We understand mostly water based paints were burnt with lesser quantities of petroleum based product," the council had said.
It later clarified that a burnt MDF board did not contain arsenic as previously stated.
"There is a contained area of contaminated water onsite which appears to be slowly evaporating and are currently assessing quantities which have discharged via our stormwater system to the Motupipi River," it said, adding that it was also testing the river for contamination levels.
In an update on Thursday afternoon, the council said staff inspections showed the contaminated run-off was confined to a drain off Motupipi Street where it would be removed.
The council said no pollutants made it into Motupipi stream or Rototai Estuary.
But it was contacting about 25 properties owners in Motupipi, to tell them they should consume bottled water as a precautionary approach until any contamination can be ruled out.
"Harmless red dye has now been placed into the stormwater system at the fire site to assess if there are any other points where potentially contaminated water may have discharged to," the council said.
Residents and businesses in Tākaka use private bores for their water supply.
"If people notice the red dye in their water supply, they should contact Tasman District Council as soon as possible," the council said.
"Ash has also fallen in the area surrounding the fire scene and property owners who collect water from roofs are advised to divert pipes away from their collection tanks."
No one was injured in the fire. Fire and Emergency is assessing the scene.