Serving parts of North West London and the Home Counties.

Groundwater levels

SouthEast Region


Central region water levels hydrograph

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

*Drought zone 1 is the LTA in Southeast region.


In Southeast region, August rainfall was 67% of the LTA. Groundwater levels remain in drought zone 1 and have declined since April at a similar rate to the LTA. During the summer months, warmer temperatures and higher soil moisture deficit (SMD) mean that less rainfall percolates down through the soil to recharge the aquifers. Consequently, Chalk groundwater recovery is mainly driven by winter rainfall. If groundwater levels follow the LTA trend, they will continue to decline until autumn 2019.

Groundwater levels may reach drought zone 2 next year under a very low rainfall scenario (60% of the LTA) although would remain above 2017 levels for the next 10 months. Average rainfall is likely to result in groundwater levels tracking just below the drought zone 1 curve until the start of the next recharge period.