Serving parts of North West London and the Home Counties.

Groundwater Levels

East Region


East region groundwater levels

*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.


Groundwater levels in the East region are currently below the drought zone 1 curve. They were declining more quickly than the drought zone, at a similar rate to the 2016 recession, though levels plateaued through August 2018, in response to wetter conditions. Although September experienced rainfall over 100 % of the LTA, Chalk groundwater levels declined through the month, suggesting that the rain which fell did not make a significant contribution to groundwater recharge. This decline has continued into October at a slightly faster rate than the LTA, the result of rainfall that was 59 % of the LTA and effective precipitation that was 34 % of the LTA.

Chalk groundwater levels were in drought zone 1 from November 2016 until March 2018. The winter of 2017/2018 experienced rainfall that was similar to the LTA and allowed groundwater levels to recover, such that levels emerged into the normal operating band for just a few months but have now returned into drought zone 1. The rapid decline in levels from May to July 2018 was caused by low rainfall (three months in a row recorded rainfall totals below 60 % of the respective monthly LTA’s) and high temperatures which allowed soil moisture deficit (SMD) to increase. Despite the higher than LTA rainfall totals for both August and September, the rainfall total from June to September inclusive was 69 % of LTA. SMD remains higher than the LTA, partly driven by the dry October. Our East region is considered drought resilient and although levels are similar to those recorded at the peak of the 2017 drought, they remain midway between the drought zone 1 and drought zone 2 curves.