It’s not an everyday sight: helicopters flying low over moorland, with what look like giant carrier bags suspended beneath.

Few people witnessing this bizarre vision, on the windswept uplands above Keighley, would associate it with the water that comes out of our taps.

Yet this operation is part of a scheme that has seen dramatic improvements in water quality in a short space of time.

It is all due to the replication of certain natural conditions, which together not only produce better water quality, but greater biodiversity and greater carbon storage. They are also an ideal environment for grouse and sheep.

Because these conditions help to filter out naturally occurring colour from water - a problem that can be costly to deal with at treatment works - they are being recreated by a team from Yorkshire Water, using moss harvested in Scotland.

“The only habitat that was consistently delivering all these outcomes was a blanket bog with 50 per cent heather cover,” says Andrew Walker Yorkshire Water’s catchment strategy manager, who has been working for the past three years with the University of Leeds to monitor and assess water quality.

“As part of the process we have been moving 5,000 bags of heather off Keighley Moor,” says Andrew, “And we will be planting moss where we have cut the heather.”

The sphagnum moss has been harvested from a donor site in Scotland. It will be planted and will become the dominant vegetation .

“Heather dries out peat and this causes a colour problem. So we want to have up to half heather, with the rest sphagnum, cotton grasses and other grasses, and dwarf shrubs such as bilberry. This will improve the water quality.”

In four years gone the area of moorland has gone from virtually no sphagnum moss to 456 square metres .

A recent report from the University of Leeds, which has sampled the water fortnightly through dip wells, showed an eight per cent improvement in water quality. “This is one of the most comprehensively monitored catchments in the country,” says Andrew.

“The water quality is improving quickly. When we set out to do this people said that it would take 15 to 20 years, yet we have seen improvements in just three.

This is, he says, in addition to other benefits associated with healthy peatlands: they are important for carbon sequestration - the capture and long-term storage of atmospheric carbon dioxide.

“Peat is carbon that has been absorbed by plant matter,” explains Andrew. “As it has no oxygen in it does not rot and is a vital carbon store. The UK has a significant proportion of the world’s peatlands, which keep carbon from being released into the atmosphere.”

Sphagnum moss absorbs carbon form the atmosphere. As the plant grows the lower roots die and turn into peat. Peat is also created from cotton grass.

The treated water - which does not taste any different - is channelled through Oldfield Water Treatment Works and supplies parts of Keighley and Oakworth.

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The work follows the completion of a five-year project targeting peat lands at locations around Bradford and other sites in Yorkshire. Plastic piles were driven into the ground, blocking off ‘peat pipes’ -naturally-occurring tubes found underground which cause slumping on the ground surface. Cutting them off raises the water table.

“The moss grow s quickly. Sphagnum acts like a blanket over the top of the peat,” says Andrew.

The projects, which have been carried out in collaboration with landowners and farming tenants, have wide benefits as they protect the carbon that is locked within the peat. Gamekeepers have commented that wetter moors deliver most grouse numbers.

Two bids for grant money are in place, which if successful will bring further funding to the work. “It is important to demonstrate to our regulators and customers that it is a wise use of money,” says Andrew. “Rather than build more treatment works we can use natural processes like this to remove colour. The more colour the more it costs us to treat.”

Other water companies and partnerships are doing similar work at different Pennine locations. “It is not only the water companies that are driving this. Many peatlands are not in as good a condition as they need to be,” says Andrew.

The cut heather will not be wasted, but will be used on Yorkshire Water’s peatland restoration scheme in Nidderdale.

Further schemes are planned for the next five years.

Adds Andrew: “The exciting thing is that just because you have run a moor for 150 years dominated by heather there is no reason why you cannot do it differently.”