Reservoir levels and rainfall figures

Last reviewed:

From 1-30 November, rainfall across the Thames catchment was 62% of the 131 year historic monthly average, with 46.9mm.

Rainfall in the last year

The graph below shows the rainfall over the last year and percentage increase and decrease against the monthly average.

Rainfall percentages for the last 12 months in relation to long term average rainfall

Where our water comes from

Across our region, we take about 65 per cent of our source water from rivers, in a process called abstraction. We then store this in large, open reservoirs (known as surface reservoirs) before putting it through our treatment process to turn it into drinking water.

The remaining 35 per cent comes from natural underground reservoirs called aquifers, from which we pump water using boreholes. This water has originally fallen as rain and sunk down into the ground in a process called recharge. These supplies from aquifers are referred to as groundwater.

Find out more about where our water comes from

November reservoir and water levels

The diagram below shows the rainfall and levels of water in the rivers, aquifers and reservoirs in our area, for the last month.

Reservoir and rainfall diagram

Water situation summary

On 30th November 2017, the Thames Regional Soil Moisture Deficit (SMD) total was 56mm which is drier than the 21mm expected for the time of year.

At the end of November, groundwater levels were generally Below Normal to Exceptionally Low for the time of year at all locations apart from an area of the Cotswolds, which remains Normal.

River flows were generally significantly below their long term averages in November. The Teddington Target Flow was maintained at 600 megalitres/day during November in agreement with the Environment Agency. 

Reservoir storage on the 30th November 2017 for London as a whole was 59% (Thames Valley 57% & Lee Valley 68%) and Farmoor storage was 94%.