Serving parts of North West London and the Home Counties.

Groundwater Levels

South East Region


South East water levels hydrograph

*The long term average (LTA) has been calculated statistically, using the long term data record for this hydrographs. The respective drought zones are used as operational triggers, and have been derived using the LTA.

*Drought zone 1 is the LTA in South East region.


Groundwater levels are currently just above the drought zone 1/LTA curve, in a reasonably healthy position and considerably higher than they were at this point in 2017. Following the low point of the 2017 drought which occurred in November, levels recovered significantly during last winter to a position above the drought zone 1/LTA curve. The June 2018 to September 2018 period inclusive has received rainfall that was 78 % of the LTA. Although June and July were very warm and dry, August and September have been much wetter, both experiencing rainfall that was in excess of 100 % of the LTA. October rainfall was 60 % of the LTA, with the majority falling during the latter half of the month. The low effective precipitation (22 % of LTA) for October was the likely result of higher than average temperatures, the rainfall pattern (a few wet days rather than persistent rainfall throughout the month) and high soil moisture deficit.

Groundwater levels are expected to decline for another month until late November 2018, according to the LTA. This will cause them to cross the drought zone 1/LTA curve. The rate and extent of the groundwater recession will be controlled by the rainfall that we receive this month. A range of possible scenarios for the next 12 months are possible but under all, groundwater levels are likely to remain above those experienced last autumn.