A NEW £1.4m water treatment scheme will be officially opened at the National Coal Mining Museum near Grange Moor.
Until now, lime was used to treat the thousands of gallons of water pumped out of the pit to keep it clear for visitors.
This was then taken by lorries to a tip.
A museum spokesman said this was not an environmentally friendly way of treating the water.
The new scheme involves treating water through reedbeds.
It is the first of its kind in this country.
The scheme will be officially opened at 10.30am on Monday, October 13, Sir John Harman, chairman of the Environment Agency and former Kirklees Council leader.