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.

Groundwater situation in the Pillhill Brook Catchment -
6 March 2026

Groundwater started to rise on 14 November 2025 so we are now officially in the 2025/26 groundwater season. 

The Environment Agency publishes monthly national and regional water situation reports. The Pillhill Brook comes under the Solent and South Downs and the EA use their Clanville Gate borehole to predict groundwater conditions within our catchment - read the latest monthly regional report here. 

In groundwater season the EA use a groundwater trigger level of 84 m at Clanville Gate to inform Southern Water of potential groundwater flooding to the sewer network in the villages surrounding Andover.  The groundwater level at Clanville Gate exceeded 84 m on 29 January 2026. With regard to potential groundwater flooding in the villages surrounding Andover it appears that the EA use a higher trigger level of 88 m. Groundwater level at Clanville Gate exceeded 89 m on 1 March and now sits at 89.17 m.

Groundwater levels at Clanville Gate rose sharply during February from 85.63 m to 89.17 m. This 3.5 m rise means that the level at Clanville Gate is rapidly catching up with the unprecendented level of  seen last year. Thankfully the start of March has been dry and the rate of groundwater rise at Clanville Gate is slowing. The level at Kimpton High View sits at 86.87 m and is now falling.

We needed more rain to recharge our aquifer so we could withstand another dry, hot summer - well the total of 732.6 mm of rainfall since last October should certainly help! 

The PBA is tracking how changes in groundwater impact brook level - click here for more details. 

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

The current Groundwater situation for Hampshire was issued on 13 February 2026 and a useful Briefing Note summarising this data is published regularly by EA's Solent & South Downs Team (see below).

Sign up to receive your own EA Flood Warnings here.

Historic Groundwater Story

With EA flood alerts being removed at groundwater levels far exceeding their publicised 84 m trigger level perhpas it is time for this level to be reassessed?

2025/26

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

Clanville Gate dropped below 84 m on 5 July and reached its lowest point of 77.91 m on 14 November 2025. 

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 we can save helps protect flow in these iconic rivers. The TUB was lifted on the 31 October 2025 having saved millions of litres of water.

2024/25

Clanville Gate dropped below 84 m on 1 September and reached its lowest point of 83 m on 26 September 2024. It then exceeded 84 m again on 21 October 2024. So groundwater only remained below the EA's triger level for less than 2 months in 2024. 

Groundwater at Clanville Gate exceeded 85 m above sea level on 26 November and 86 m on 1 December 2024 and the EA started issuing regular briefings on groundwater flooding. Heavy rainfall over the last 3 months of 2024 caused groundwater levels to rise rapidly and the exceptionally wet start to 2025 meant groundwater was heading toward the unprecedented levels seen in the winter of 2024 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 84 m on 5 July 2025. 

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

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