Current UK groundwater use

Groundwater contributes 30 per cent of public supply water in England. In volume terms, this is over six thousand million litres per day (6064 Ml/d): enough to fill 2500 Olympic-sized swimming pools every day, or run a dishwasher 400 million times! In Wales and Scotland groundwater provides about five per cent of public supply. Across the UK groundwater also provides a crucial source of private supplies for domestic, agricultural and industrial use.

The volumes of groundwater used daily in England and Wales are shown in Figure 1.

Some of the water supply regions are large, such as the area supplied by Anglian Water (Figure 2). The data cover the whole region and thus aggregate areas that are more dominated by groundwater supply (in the case of Anglian Water, this is mainly from the Chalk aquifer) with those that are more dominated by surface water (e.g. Rutland Water and Grafham Water reservoirs, River Trent).


Groundwater deployable output, Ml/d 2015
Water supply company boundaries

Groundwater for public supply in England — influence of geology

The most detailed information we have is for England, which shows regional variations in the amount and proportion of groundwater used for public supply (Figure 3). We have calculated the 'groundwater as a percentage of deployable output' (DO) for each water company by comparing the sum of all groundwater-source DOs to the sum of all of the company's source DOs, using data from the 2015 WRMPs. The proportion of deployable output that is provided by groundwater varies from 100 per cent in Cambridge Water and Cholderton Water to just over four per cent in Northumberland Water.

Groundwater is the largest component of supply for eight water supply companies, who together serve a population of over eight million people. The regional variations are largely related to the availability of groundwater and surface water. The highly productive Chalk and Permo-Triassic sandstones are the major sources of groundwater for public supply — these aquifers correspond to the bulk of the dark blue shade on the simplified aquifer map shown in Figure 4.

Groundwater as a percentage of deployable output, 2015
Simplified aquifer map of UK

Groundwater use in Scotland, Wales and Northern Ireland

We have limited information about groundwater use for public supply in Scotland, Wales and Northern Ireland. These countries have an ample supply of surface water, while aquifers tend to be less productive and/or more localised. Groundwater in Scotland, Wales and Northern Ireland is most significant for users of private supplies, many of whom are reliant on their private water source, as their property is not connected to the public supply network.

Groundwater use in Scotland, 2014

Scotland's public water supply is dominated by surface water, with only about five per cent from groundwater (Ó Dochartaigh et al., 2015). Approximately 100 boreholes and springs are used for public supply across Scotland, and these groundwater sources supply some of Scotland's major rural towns (Ó Dochartaigh et al., 2015).

The total volume of public supply from groundwater in Scotland is thought to have been some 235 Ml/d in 2004 (Figure 5) compared with 6064 Ml/d in England (2015). A tabulated comparison of groundwater volumes in public supply is provided on our facts and figures page.

Groundwater supplies about five per cent of public supply water in Wales, which equates to approximately 40 Ml/d. "Most groundwater sources are operated conjunctively with surface water sources. However, some groundwater sources are critical in supplying local areas that cannot be supplied by other means." (Welsh Water WRMP, 2015). Welsh Water has three water resource zones (WRZs) where groundwater is the main source of water:

  • Brecon Portis WRZ, which supplies 12 000 people
  • Pilleth WRZ, which supplies 8000 people
  • Vowchurch WRZ, which supplies 7000 people

Groundwater is a negligible component of the Northern Ireland public water supply: just 0.6 per cent according to Northern Ireland Water (2013 report).

Groundwater for private supply

There are vast numbers of private supplies across the UK that abstract groundwater for domestic, agricultural and industrial uses. Groundwater provides about 70 per cent of private supplies in Scotland, to at least 330 000 people (Ó Dochartaigh et al., 2015). More than 4000 boreholes, as well as some large springs, are used for large private, industrial or agricultural supplies; many more — approximately 20 000 — boreholes, small springs and wells provide private water supplies for at least 80 000 people (Ó Dochartaigh et al., 2015).

There are about 8000 properties which do not have a public water supply in Northern Ireland; the majority of these will be using some form of groundwater source (Review of financial assistance for domestic properties not served by a water main: a consultation document. Department for Regional Development Northern Ireland. 2010).

Why do we use groundwater?

Groundwater has various advantages over surface water sources such as rivers, for example:

  • in areas where aquifers are present, they are usually accessible over large areas, so you can sink a borehole almost anywhere and have a water supply just where you need it
  • groundwater often needs less treatment than rivers, being naturally filtered and (depending on the construction of the source) potentially less vulnerable to surface contaminants such as animal waste

The past and the future

Water companies are required to look forward in their WRMPs, considering pressures and impacts to 2040. Our brief history page looks back to the 1800s, considering how the ways in which we have exploited groundwater, and the uses we have abstracted it for, have changed over time.

Contact

Please contact Matthew Ascott for further information.