From 1-31 December, rainfall across the Thames catchment was 107% of the 134 year historic monthly average, with 79.9mm.
Rainfall in the last year
The graph below shows the rainfall over the last year and percentage increase and decrease against the monthly average.
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.
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.
Water situation summary
On 31st December, the Thames Regional Soil Moisture Deficit (SMD) total was 8 mm which is slightly higher (i.e. drier) than expected for the time of year.
At the end of December, groundwater levels were generally below average.
Generally, river flows were below their long term averages in December. The Teddington Target Flow, which determines the minimum flow that must be maintained over Teddington weir, rose from 600 Ml/d to 800 Ml/d in December.
Reservoir storage on the 31st December 2018 for London as a whole was 97% (West London 86% & Lee Valley 93%) and Farmoor storage was 88%.