Rob Lawson, Director at Artesia Consulting Ltd outlines a new collaborative project currently being undertaken by 15 water companies and the Environment Agency which is expected to yield valuable insights quantifying the impacts of the summer heatwave on water demand.

Rob Lawson: The hot dry weather of summer 2018 may now be becoming a distant memory to most of us, but water companies will be working with Artesia to quantify the impact of the heatwave on water demand, and provide insight, data and strategies to provide resilience against similar future events.

This will be invaluable for water companies as they face future challenges, when climate change is expected to result in more frequents summers like 2018.

This work has been initiated after the Met Office confirmed that 2018 was the joint hottest on record together with 2006, 2003 and 1976. For the UK 2018 is likely to finish in the top 15 driest summers, and top 5 driest for England. It is also in the top 5 sunniest for the UK. This led to unprecedented demand for several companies, with Southern Water reporting that they were supplying 100 million more litres of water during the heatwave compared with an average day in 2017 . Thames Water reported pumping an extra 450 million litres of water into its network – a 17 per cent increase – enough to typically supply 800,000 homes .

United Utilities announced that it would impose a hosepipe ban (known as a Temporary Use Ban), which was due to come into force on 5 August. This ban was lifted on 2 August after rainfall and a reduction in customers’ water usage. Northern Ireland Water did impose a ban for three weeks, from 29 June to 19 July.

Water resource pressures eased in August as temperatures began to fall, but reservoir stocks continued to decrease and were more than 20% below the late August average in Walesand parts of the Pennines. Combined stocks for England and Wales were the fourth lowest for late August in a record from 1988 .The Environment Agency responded to a 330% increase in drought-related incidents to protect wildlife and rescue fish .

Currently fifteen water companies and the Environment Agency are taking part in the collaborative project, being delivered by Artesia, which will analyse water demand and weather data from across England and Wales. The study will look at the total amount of water put into supply, consumption by households and non-households and leakage, and how these were affected by the weather during prolonged hot and dry spell.

The work will explore relationships between the various types of water demand and temperature, days without rain, sunshine/solar radiation and soil moisture deficit. The effect of metering on peak demand will also be explored. Comparisons will be made between regions and with historic dry weather and drought events. The study will also include a survey of companies to collect qualitative information – for example including their communications with customers.

An important aspect of the work will be to look at which factors dampen the effects of peak weather on demand, and how these can be used to mitigate the impact of future peak summers. The work will also consider how the water demand in 2018 compares with the peak demand used for planning scenarios in water resource and drought planning.

The idea for the project came from Mumin Islam,Water Resources Planning Manager at Affinity Water who commented:

“Companies’ business plans are in now, so we can focus on reviewing the unusually high demands in July and August 2018 and get valuable insights from this project to ensure future resilience.”

Dene Marshallsay, Project Director for Artesia added:

“This project is a great example of water industry collaboration to make use of readily available data whilst the experiences of the summer are still fresh in everyone’s minds”.

Interim project outputs will be presented in October ahead of Defra’s expected consultation on targets for per capita consumption. The main findings of the study will be made public in early 2019.