UK water
The deepest Hydrionis geography. Water is devolved, so there is no single UK water system — there are four, with different regulators, different ownership and different charging.
The rainfall gradient
Scotland receives roughly twice England’s rainfall. The population is concentrated where the rain is not.
View the data behind this chart
| Subject | Value (mm) | Notes |
|---|---|---|
| England | 798 | — |
| Scotland | 1,391 | — |
| Wales | 1,446 | — |
| Northern Ireland | 1,106 | — |
Parts of Essex and Cambridgeshire receive under 600 mm a year — comparable with parts of Spain. Combine that with the highest population density in the UK and you have the central fact of English water resources: the water is in the wrong place relative to the people.
Two long records
Hydrionis holds English rainfall from 1836 and river flow on the Thames at Kingston from 1883, ingested directly from the Met Office and the Environment Agency. Records this long are what make it possible to say whether a dry year is unusual, rather than only that it was dry.
- Annual rainfall against the 1991–2020 normal
- 10-year mean
A shaded drought does not always coincide with a low annual total. Droughts are made by the timing of rainfall and by what was already in the ground, not by the calendar-year sum — 1976 is visible here, but the drought began in 1975 and its severity came from two dry winters in succession.
View the data behind this chart
| Period | Annual rainfall against the 1991–2020 normal (%) | 10-year mean (%) |
|---|---|---|
| 1836 | 1.83 | — |
| 1837 | -14.2 | — |
| 1838 | -12.6 | — |
| 1839 | 5.69 | — |
| 1840 | -20.9 | — |
| 1841 | 11.2 | -8.24 |
| 1842 | -16.3 | -8.93 |
| 1843 | -4.28 | -8.95 |
| 1844 | -25.0 | -6.09 |
| 1845 | -7.78 | -7.67 |
| 1846 | -5.11 | -7.50 |
| 1847 | -14.4 | -10.4 |
| 1848 | 16.0 | -6.67 |
| 1849 | -10.0 | -7.26 |
| 1850 | -19.2 | -7.54 |
| 1851 | -18.1 | -9.18 |
| 1852 | 21.3 | -9.75 |
| 1853 | -10.2 | -9.85 |
| 1854 | -27.8 | -13.9 |
| 1855 | -24.1 | -13.6 |
| 1856 | -10.9 | -10.6 |
| 1857 | -15.4 | -10.1 |
| 1858 | -25.0 | -12.7 |
| 1859 | -6.33 | -12.8 |
| 1860 | 10.7 | -12.8 |
| 1861 | -13.5 | -11.0 |
| 1862 | -4.83 | -9.11 |
| 1863 | -11.3 | -8.43 |
| 1864 | -27.7 | -6.52 |
| 1865 | -5.62 | -6.24 |
| 1866 | 7.78 | -9.83 |
| 1867 | -8.60 | -9.56 |
| 1868 | -5.79 | -5.79 |
| 1869 | -3.59 | -6.37 |
| 1870 | -25.1 | -5.02 |
| 1871 | -10.7 | -3.95 |
| 1872 | 32.8 | -3.99 |
| 1873 | -17.1 | -1.55 |
| 1874 | -14.2 | -0.964 |
| 1875 | 5.05 | -0.655 |
| 1876 | 7.33 | 2.27 |
| 1877 | 15.9 | 3.32 |
| 1878 | 0.046 | 1.72 |
| 1879 | -0.494 | 3.44 |
| 1880 | 4.11 | 2.86 |
| 1881 | -0.207 | 1.62 |
| 1882 | 16.8 | 1.39 |
| 1883 | 0.149 | -3.34 |
| 1884 | -20.0 | -4.36 |
| 1885 | -7.38 | -5.70 |
| 1886 | 5.03 | -7.77 |
| 1887 | -31.4 | -7.41 |
| 1888 | -10.1 | -10.4 |
| 1889 | -13.9 | -12.7 |
| 1890 | -16.6 | -10.7 |
| 1891 | 3.40 | -11.1 |
| 1892 | -13.1 | -13.1 |
| 1893 | -22.7 | -10.6 |
| 1894 | -0.253 | -11.6 |
| 1895 | -11.8 | -11.6 |
| 1896 | -14.1 | -9.89 |
| 1897 | -7.21 | -12.3 |
| 1898 | -20.3 | -13.2 |
| 1899 | -13.1 | -8.93 |
| 1900 | 0.218 | -10.7 |
| 1901 | -20.3 | -11.7 |
| 1902 | -22.4 | -11.0 |
| 1903 | 19.9 | -11.0 |
| 1904 | -17.6 | -10.7 |
| 1905 | -22.4 | -9.68 |
| 1906 | -7.26 | -9.36 |
| 1907 | -6.85 | -8.60 |
| 1908 | -17.6 | -4.84 |
| 1909 | -2.54 | -7.98 |
| 1910 | 3.38 | -6.24 |
| 1911 | -12.6 | -3.83 |
| 1912 | 15.2 | -2.46 |
| 1913 | -11.5 | -2.76 |
| 1914 | -0.207 | -1.15 |
| 1915 | 1.69 | -1.29 |
| 1916 | 6.51 | -1.93 |
| 1917 | -9.89 | -4.24 |
| 1918 | -1.46 | -6.08 |
| 1919 | -3.97 | -4.66 |
| 1920 | -3.02 | -3.64 |
| 1921 | -35.7 | -4.08 |
| 1922 | -3.18 | -5.39 |
| 1923 | 2.67 | -3.11 |
| 1924 | 9.92 | -2.49 |
| 1925 | -2.64 | -2.96 |
| 1926 | -6.62 | -1.93 |
| 1927 | 12.9 | 1.77 |
| 1928 | 4.72 | 1.56 |
| 1929 | -8.63 | -1.23 |
| 1930 | 7.30 | -3.50 |
| 1931 | 1.25 | -2.86 |
| 1932 | -5.24 | -2.21 |
| 1933 | -25.2 | -3.44 |
| 1934 | -12.8 | -4.68 |
| 1935 | 3.74 | -3.33 |
| 1936 | -0.138 | -4.76 |
| 1937 | 0.575 | -6.03 |
| 1938 | -7.62 | -6.86 |
| 1939 | 4.89 | -5.72 |
| 1940 | -7.01 | -5.09 |
| 1941 | -11.5 | -6.92 |
| 1942 | -13.5 | -5.93 |
| 1943 | -13.8 | -7.63 |
| 1944 | -6.48 | -7.00 |
| 1945 | -14.6 | -9.31 |
| 1946 | 9.74 | -8.18 |
| 1947 | -16.3 | -5.69 |
| 1948 | -1.36 | -5.19 |
| 1949 | -18.2 | -6.01 |
| 1950 | 4.34 | -4.04 |
| 1951 | 13.4 | -4.61 |
| 1952 | -8.55 | -6.58 |
| 1953 | -22.1 | -5.62 |
| 1954 | 13.2 | -4.72 |
| 1955 | -20.2 | -4.48 |
| 1956 | -10.0 | -2.70 |
| 1957 | -6.75 | -4.80 |
| 1958 | 7.64 | -5.55 |
| 1959 | -15.8 | -4.24 |
| 1960 | 22.1 | -8.05 |
| 1961 | -7.60 | -5.47 |
| 1962 | -16.0 | -3.55 |
| 1963 | -9.01 | -2.43 |
| 1964 | -24.9 | -2.81 |
| 1965 | 5.61 | -1.79 |
| 1966 | 9.13 | -4.42 |
| 1967 | 4.47 | -5.25 |
| 1968 | 3.83 | -4.69 |
| 1969 | -5.54 | -6.13 |
| 1970 | -4.25 | -3.06 |
| 1971 | -15.8 | -5.71 |
| 1972 | -10.4 | -8.21 |
| 1973 | -23.4 | -8.93 |
| 1974 | 5.74 | -9.91 |
| 1975 | -20.9 | -8.95 |
| 1976 | -15.9 | -8.34 |
| 1977 | -2.66 | -6.28 |
| 1978 | -6.03 | -5.14 |
| 1979 | 4.11 | -3.60 |
| 1980 | 1.78 | -4.59 |
| 1981 | 4.82 | -3.20 |
| 1982 | 0.943 | -1.20 |
| 1983 | -7.98 | -1.21 |
| 1984 | -4.13 | -0.923 |
| 1985 | -6.98 | -2.87 |
| 1986 | 4.07 | -4.37 |
| 1987 | -2.68 | -6.58 |
| 1988 | -3.20 | -6.63 |
| 1989 | -15.3 | -5.44 |
| 1990 | -13.2 | -4.53 |
| 1991 | -17.3 | -5.19 |
| 1992 | 0.437 | -7.81 |
| 1993 | 3.90 | -8.54 |
| 1994 | 5.03 | -7.11 |
| 1995 | -13.6 | -4.82 |
| 1996 | -22.2 | -0.754 |
| 1997 | -9.95 | 0.895 |
| 1998 | 11.1 | 2.42 |
| 1999 | 7.55 | -0.217 |
| 2000 | 27.5 | -0.493 |
| 2001 | -0.839 | -0.566 |
| 2002 | 15.7 | 1.36 |
| 2003 | -22.5 | 3.08 |
| 2004 | 2.28 | 3.25 |
| 2005 | -14.3 | 2.55 |
| 2006 | -2.93 | -1.85 |
| 2007 | 7.25 | -3.57 |
| 2008 | 12.8 | -2.20 |
| 2009 | 0.529 | -0.608 |
| 2010 | -16.5 | 0.462 |
| 2011 | -18.1 | 1.86 |
| 2012 | 29.4 | 1.61 |
| 2013 | -6.55 | 0.370 |
| 2014 | 13.0 | -1.77 |
| 2015 | -0.368 | -0.566 |
| 2016 | -5.37 | 2.45 |
| 2017 | -5.16 | 4.34 |
| 2018 | -8.63 | 0.354 |
| 2019 | 12.6 | 3.32 |
| 2020 | 13.7 | 3.93 |
| 2021 | 0.851 | 3.14 |
| 2022 | -10.5 | — |
| 2023 | 23.1 | — |
| 2024 | 19.1 | — |
| 2025 | -8.31 | — |
- Annual mean flow
- 10-year mean
Flow at Kingston is a property of this gauge on this reach, not of the Thames as a whole, and it is affected by abstraction upstream — London's water is taken from the river above this point, so the record measures what is left as well as what fell.
View the data behind this chart
| Period | Annual mean flow (m³/s) | 10-year mean (m³/s) |
|---|---|---|
| 1884 | 47.8 | — |
| 1885 | 58.0 | — |
| 1886 | 78.8 | — |
| 1887 | 56.3 | — |
| 1888 | 61.3 | — |
| 1889 | 64.6 | 57.6 |
| 1890 | 38.1 | 60.6 |
| 1891 | 67.9 | 60.8 |
| 1892 | 55.7 | 58.0 |
| 1893 | 47.3 | 59.7 |
| 1894 | 78.1 | 57.0 |
| 1895 | 60.0 | 55.2 |
| 1896 | 51.0 | 57.3 |
| 1897 | 73.2 | 54.6 |
| 1898 | 33.8 | 51.8 |
| 1899 | 47.3 | 58.0 |
| 1900 | 59.2 | 57.8 |
| 1901 | 40.4 | 54.8 |
| 1902 | 27.5 | 54.8 |
| 1903 | 110 | 53.4 |
| 1904 | 76.0 | 56.2 |
| 1905 | 30.4 | 57.0 |
| 1906 | 51.1 | 59.7 |
| 1907 | 58.8 | 61.3 |
| 1908 | 62.2 | 69.0 |
| 1909 | 55.0 | 66.1 |
| 1910 | 85.7 | 64.8 |
| 1911 | 56.9 | 73.1 |
| 1912 | 104 | 79.9 |
| 1913 | 81.3 | 82.0 |
| 1914 | 62.0 | 83.1 |
| 1915 | 114 | 87.4 |
| 1916 | 118 | 86.1 |
| 1917 | 80.3 | 83.3 |
| 1918 | 73.2 | 77.1 |
| 1919 | 98.2 | 76.6 |
| 1920 | 72.4 | 80.9 |
| 1921 | 28.9 | 79.0 |
| 1922 | 42.8 | 75.6 |
| 1923 | 75.9 | 78.5 |
| 1924 | 105 | 80.7 |
| 1925 | 95.8 | 76.8 |
| 1926 | 84.0 | 77.7 |
| 1927 | 109 | 82.9 |
| 1928 | 95.5 | 86.1 |
| 1929 | 59.5 | 84.5 |
| 1930 | 80.5 | 76.0 |
| 1931 | 81.5 | 73.1 |
| 1932 | 75.0 | 73.9 |
| 1933 | 59.0 | 74.4 |
| 1934 | 20.3 | 68.9 |
| 1935 | 67.1 | 72.4 |
| 1936 | 92.1 | 72.5 |
| 1937 | 113 | 72.3 |
| 1938 | 41.0 | 70.6 |
| 1939 | 94.7 | 69.6 |
| 1940 | 80.9 | 70.5 |
| 1941 | 79.3 | 67.7 |
| 1942 | 58.2 | 65.5 |
| 1943 | 49.7 | 62.5 |
| 1944 | 28.5 | 62.1 |
| 1945 | 39.4 | 56.8 |
| 1946 | 70.7 | 54.7 |
| 1947 | 82.5 | 58.9 |
| 1948 | 37.5 | 59.7 |
| 1949 | 40.8 | 58.7 |
| 1950 | 60.8 | 62.7 |
| 1951 | 121 | 64.4 |
| 1952 | 65.7 | 61.4 |
| 1953 | 39.6 | 59.1 |
| 1954 | 69.3 | 63.7 |
| 1955 | 56.2 | 66.0 |
| 1956 | 40.4 | 70.5 |
| 1957 | 59.3 | 65.4 |
| 1958 | 83.7 | 64.2 |
| 1959 | 64.3 | 66.6 |
| 1960 | 105 | 64.4 |
| 1961 | 69.9 | 63.0 |
| 1962 | 53.8 | 67.8 |
| 1963 | 63.7 | 70.2 |
| 1964 | 47.8 | 71.1 |
| 1965 | 41.8 | 71.8 |
| 1966 | 88.8 | 67.2 |
| 1967 | 83.1 | 67.4 |
| 1968 | 92.5 | 67.9 |
| 1969 | 71.7 | 63.9 |
| 1970 | 59.2 | 67.3 |
| 1971 | 71.5 | 70.0 |
| 1972 | 58.5 | 63.3 |
| 1973 | 24.1 | 63.7 |
| 1974 | 81.6 | 61.0 |
| 1975 | 68.6 | 62.2 |
| 1976 | 22.0 | 62.7 |
| 1977 | 87.7 | 62.9 |
| 1978 | 65.3 | 65.2 |
| 1979 | 83.6 | 68.6 |
| 1980 | 63.9 | 67.3 |
| 1981 | 73.8 | 66.7 |
| 1982 | 81.2 | 68.4 |
| 1983 | 58.6 | 64.2 |
| 1987 | 67.8 | 60.2 |
| 1988 | 62.7 | 56.7 |
| 1989 | 39.3 | 57.2 |
| 1990 | 45.8 | 56.5 |
| 1991 | 24.9 | 51.7 |
| 1992 | 49.2 | 47.6 |
| 1993 | 68.9 | 47.2 |
| 1995 | 67.1 | 51.6 |
| 1996 | 33.1 | 58.1 |
| 1997 | 17.6 | 61.2 |
| 1998 | 64.0 | 64.4 |
| 2000 | 107 | 64.6 |
| 2001 | 104 | 59.8 |
| 2002 | 77.0 | 62.4 |
| 2003 | 56.8 | 67.4 |
| 2004 | 50.7 | 71.5 |
| 2005 | 21.0 | 70.8 |
| 2007 | 93.5 | 63.0 |
| 2008 | 82.6 | 60.3 |
| 2009 | 58.9 | 60.7 |
| 2010 | 56.8 | 66.7 |
| 2011 | 28.6 | 65.8 |
| 2012 | 77.0 | 69.9 |
| 2013 | 81.6 | 63.6 |
| 2014 | 117 | 59.2 |
| 2015 | 40.9 | 62.0 |
| 2016 | 62.4 | 68.6 |
| 2017 | 30.5 | 71.5 |
| 2022 | 38.6 | — |
| 2023 | 86.5 | — |
| 2024 | 124 | — |
| 2025 | 56.8 | — |
Kingston is one of several hundred stations Hydrionis holds records for, alongside observation boreholes going back to 1836.
The four systems
| Nation | Ownership | Economic regulator | Quality regulator | Household charging |
|---|---|---|---|---|
| England | Private regional monopolies | Ofwat | DWI | Separate water bill |
| Scotland | Publicly owned corporation | WICS | DWQR | Collected with council tax |
| Wales | Company limited by guarantee, no shareholders | Ofwat | DWI | Separate water bill |
| Northern Ireland | Government-owned company | Utility Regulator | DWI NI | No separate household charge |
Leakage by company
How leakage is measured →Absolute leakage scales with company size and must not be used to rank companies against each other. Leakage is also a residual of a water balance rather than a direct measurement, so it carries real uncertainty.
View the data behind this chart
| Subject | Value (Ml/d) | Notes |
|---|---|---|
| Scottish Water | 455 | — |
| Thames Water | 570 | — |
| Severn Trent Water | 400 | — |
| United Utilities | 415 | — |
| Yorkshire Water | 260 | — |
| Anglian Water | 175 | — |
| Southern Water | 85.0 | — |
| South West Water | 80.0 | — |
| Wessex Water | 60.0 | — |
| Northumbrian Water | 130 | — |
| Dŵr Cymru Welsh Water | 165 | — |
| Affinity Water | 145 | — |
| South East Water | 65.0 | — |
Bills
How bills work →View the data behind this chart
| Period | Average household bill (GBP/yr) |
|---|---|
| 2020 | 396 |
| 2021 | 408 |
| 2022 | 419 |
| 2023 | 448 |
| 2024 | 473 |
| 2025 | 603 |
Storm overflows
Storm overflows explained →Monitoring coverage rose from a small minority of overflows in 2016 to effectively all of them by 2023. Part of the increase reflects increased measurement rather than increased discharge — and that is a qualification, not a defence.
View the data behind this chart
| Period | Recorded spills (spills/yr) |
|---|---|
| 2020 | 403,000 |
| 2021 | 372,500 |
| 2022 | 301,000 |
| 2023 | 464,000 |
| 2024 | 450,000 |
Why UK water hardness varies so much
Explore the UK
The monitoring network →
Every river gauge and observation borehole Hydrionis holds a record for, mapped and ranked by how far back the record runs.
My water →
Find your supplier, your likely hardness, and what is known about the water where you live.
Water companies →
28 utilities with ownership, regulation, sources and performance.
Nations, councils and basins →
Every UK administrative unit, service area and river basin district Hydrionis holds.
UK water explained →
The full explainer on how the four systems differ and why the rainfall gradient matters.
Fines and enforcement →
Regulatory and criminal action against UK water companies.
Projects →
New reservoirs, transfers and network schemes, tracked from open planning and procurement sources.