Yorkshire Water on climate changes and managing reservoirs and water supply during drought

On August 26, a hosepipe ban came into force for Yorkshire Water customers, brought on by the lowest rainfall in parts of Yorkshire since records began more than 130 years ago.

Granville Davies, clean water and catchment strategy manager at the company, is among those involved in managing water supply. “We’ve had six months now of below average rainfall,” he says, explaining why the ban is still in place.

“So ever since the beginning of March, every month has been below average rainfall, some significantly so. We think August will turn out as less than half of what we usually have.

"We start to see reduced reservoir levels to start with - we’re still abstracting water from reservoirs for water supply, but there’s less water going into them because of the dry weather, so the reservoir levels start to drop. And what we have seen this year is a prolonged drop in reservoir levels.”

Nearly half of the water the company supplies comes from reservoirs, which collect and store water running off moorlands before it is piped into treatment works for cleaning processes. The company says these are currently only around 40 per cent full.

Somewhere around a quarter to a third of water comes from the region’s rivers and the remainder comes from underground aquifers, which collect groundwater.

Granville explains how the company’s first response to reduced reservoir levels is to take more water from rivers, which he says has been happening since April. But as the dry weather continued, the company’s drought plan came into play and the hosepipe ban was put into place.

The ban, the company explains, allows it to apply for drought permits from the Environment Agency, which means it can abstract more water from rivers and reduce flows out of reservoirs.

“We’ve had exceptionally hot weather at times this summer, which pushes demand up a lot so we’ve seen reservoir levels continue to drop as we’ve gone through the summer period," Granville says. “We’ve also seen river levels come down a bit so they weren’t always available to fully support the reservoirs in the way that we’d like because the weather’s been so dry.”

“We have seen rain in the past week but unfortunately one week of rain is not enough to offset six months of dry weather,” he adds. "Nevertheless it is a positive thing - it helps to rewet the ground and it has led to some increase of river flow which has been beneficial.”

Water companies in England must prepare and maintain what is called a water resources management plan, setting out how they intend to achieve a secure supply of water for customers and “a protected and enhanced environment”. It must be prepared at least every five years, reviewed annually and include the forecasted supply and demand over a minimum of 25 years.

Granville explains how the Yorkshire Water plan takes into consideration factors such as climate change, protecting the environment by not over-abstracting water, population growth and changing trends in how people use water.

“What we’re seeing with modelling for that plan is the latest climate change data is showing a much bigger impact on supply than previous climate change data has shown,” he says. “What that means is we’re having to explore more options for both reducing customer demand and potentially increasing supply.

"For us it’s likely to mean more activity working with customers to try and encourage more sensible use of water, reducing water use in the home, but also potentially looking at other new sources of water that we’re not currently using that we could bring into supply.”

He adds: “We know that climate change is going to impact on many aspects of the environment and the water cycle in particular...The trend will definitely be towards more summers like the one we have had this year, with periods of much drier weather than we’re used to and potentially periods of exceptionally hot weather like we’ve seen this summer.”