Groundwater

The Pillhill Brook Association (PBA) monitors groundwater behaviour within our catchment on a weekly basis. Groundwater level is important because it dictates the height of water in the brook and hence flow and also how quickly rainfall will soak away into the ground, preventing flooding. We monitor levels at 5 local boreholes: 

1. Clanville Gate in Clanville

2. High View in Kimpton

3. Stanbury Road Water Pumping Station (WPS) in Kimpton

4. Haydown Farm in East Cholderton

5. Monxton WPS in Monxton

See map below for locations.

Current groundwater situation in the Pillhill Brook Catchment - 16 August 2025

Outside of groundwater season the Environment Agency publishes monthly national and regional water situation reports on Drought and Water Availablility. The PIllhill Brook comes under the Solent and South Downs - read the latest regional report here.

This year Clanville Gate dropped below 84 m on 5 July and below 83 m on 22 July.  Level currently sits at 82.4 m - the GW level at Clanville Gate did not drop below 83 m last year! 

Having suffered several droughts and more hot and dry weather forecast Southern Water put hosepipe restrictions or a Temporary Usage Ban (TUB) in place on 21 July 2025 to help conserve water supplies. As most of our drinking water comes from abstraction points on the River Test and Itchen any water you can save will be helping to protect flows in these iconic rivers.  

Clanville Gate is now falling at a steady rate of 6 cm per day and Kimpton High View at 4 cm per day. 

In the valley the rate of fall is following a combination of both Clanville and Kimpton trends albeit at a much reduced rate (N.B. the scale on the graph below are different for the main and valley boreholes). It will be interesting to see how these levels relate to brook depth and the northern stretch of the Pillhill Brook has already stopped flowing which is quite normal. The PBA is now tracking how brook levels respond to falling groundwater (see Brook Levels). 

All data indicates that we be in a better position come the 25/26 groundwater season, with levels likely to be starting to rise from a point 3 m lower than last season.

In groundwater season the EA use a groundwater trigger level of 84 m at Clanville Gate borehole to inform them of potential groundwater flooding in the villages surrounding Andover.  

Click on Andover Villages (Clanville) for the latest groundwater data. 

The last Groundwater situation for Hampshire in 2025 was issued on 11 April 2025.

The last flood alert in 2025 was removed on Sunday 4 May 2025 with a groundwater level at Clanville Gate of 87.69 m. 

Sign up to receive your own EA Flood Warnings here.

Historic Groundwater Story

2024/25

The EA's groundwater trigger point of 84 m above sea level was exceeded at Clanville Gate on 21 October 2024. 

Groundwater at Clanville Gate exceeded 85 m above sea level on 26 November and 86 m on 1 December and the Environmental Agency started issuing regular briefings on groundwater flooding. Heavy rainfall over the last 3 months of 2024 meant that groundwater levels continued to rise rapidly and the exceptionally wet start to 2025 meant that groundwater was heading toward the unprecedented levels seen last year of just over 91 m. However March was exceptionally dry - only 6 mm of rain fell on the catchment versus an expected average of 59 mm. Combined with the trees coming into leaf groundwater peaked at 89.96 m on 8 March 2025. Groundwater level at Clanville Gate fell below 88 m on 29 April 2025. 

2023/24

The last Groundwater situation for Hampshire in 2024 was issued on 6 June 2024. 

The Environmental Agency (EA) use the groundwater level at Clanville Gate to inform them of the risk of flooding in the villages surrounding Andover. The EA also use a groundwater level of 84 m above sea level as the trigger point with Southern Water for the risk of major groundwater infiltration in the sewer network. 

The last flood alert in 2024 was removed on Tuesday 28 May 2024 with a groundwater level at Clanville Gate of 89.27 m.