Two-thirds of France's groundwater sits below seasonal norms, BRGM warns

Groundwater falls below seasonal norms

The Bureau de recherches géologiques et minières (BRGM), France's national geological service, said on Thursday 8 October 2026 in its monthly bulletin that the situation of the country's groundwater remains very worrying after an exceptional drought. The bulletin is based on observations made on 1 October, and 66% of observation points sit below monthly seasonal norms. Ouest France reports that more than 20% of sensors show a very low level. The BRGM says drainage continues across the territory at a time of year when the usual trend is the start of recharge.

With 66% of observation points below monthly normals, the situation of the groundwater remains very worrying. The drainage continues across the whole territory where the usual trend at this time of year is the start of recharge.

The bulletin distinguishes between two types of aquifer. Inertial aquifers, which can take months or even years to change direction, continue to fall. Reactive aquifers, which can respond to rainfall within weeks, show declining levels in almost all cases.

Only 7% of sensors record recharge

Only 7% of sensors currently record a recharge, compared with 30% in September 2025, according to Ouest France.

September 2025

30

Current (8 October 2026)

7

September 2025

30 %

Current (8 October 2026)

7 %

Specialists quoted by the newspaper say the summer drought is part of the natural cycle of aquifers, and that the coming weeks will decide the outcome. If the drought continues, the aquifers will drop off, and the current stock is low, which makes the system vulnerable in future. Météo France has planned a scenario that is hotter but also wetter. Specialists say upcoming rain will be important to rewet the soils, although infiltration will be harder on dry ground, and that the deficit can still be filled in the coming months. Ouest France says the situation is as worrying as in 2022, though the aquifers affected this year are not the same.

Regional picture and restrictions

The level is degraded across most of the territory, with the South-East as the exception, including the Vistrenque formations in southern Gard and the Astian sands of Valras-Agde around Hérault. Levels are described as very low for aquifers in the Limousin basement, Morvan, Livradois, Forez and Vivarais, the Champagne chalk, the Jura limestones, the Vosges sandstones, and the Triassic limestones of Lorraine and the northern Alsace plain. VigiEau counts 79 departments in 'crisis' and 14 in 'reinforced alert', with restrictions on water use.

Crisis

79

Reinforced alert

14

Crisis

79

Reinforced alert

14

Summer and tap water supply

France recorded its hottest summer ever, with a mean 24-hour temperature of 24°C, 3.6°C above the 1991-2020 normals and ahead of 2003 and 2022. Few rains were recorded, which caused the significant drought. Ouest France notes that the intensity of this summer's heatwaves does not necessarily affect groundwater directly, and that aquifers had a fairly comfortable reserve built by rainy winters in past years, unlike the soils. The ministry of Ecological Transition said on Wednesday that 94,000 people in mainland France were without tap water at the end of September, 30,000 more than at the start of the month.