Serving parts of North West London and the Home Counties.

Groundwater levels

Central 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.


Groundwater levels in our Central region remain in drought zone 2, below the level that they were at this point in 2018. Following the dry start to the year, March was wetter, and we have received over 120% of the LTA rainfall for the month. Despite receiving above average rainfall, groundwater levels have continued to recover at a lesser rate than the LTA trend, the result of dry conditions in the preceding months. Dry weather at the end of March has increased the soil moisture deficit (SMD) again. This is likely to effect recharge rates for April as higher than average SMD decreases the recharge component from rainfall, as more water is absorbed by the soil.

Continued groundwater level recovery into April is expected if we receive at least 60% of LTA rainfall, however the extent of this will vary with the rainfall pattern and even with 120% LTA rainfall, groundwater levels are unlikely to recover out of drought zone 2 this summer. A rainfall pattern of approximately 100% of the LTA could potentially see groundwater levels approaching drought zone 3 in late autumn 2019, while under a 60% LTA scenario we would likely approach drought zone 3 in late summer, with lower levels than during the recession period of 2017.