Map of aquifer levels in mainland France on 15 October 2025.
© BRGM
Trends observed on piezometers on 15 October 2025.
© BRGM
Trends
The recharge period looked to be starting positively at the end of August and in September. The conditions seemed set for the recharge period to begin in all aquifers during the month of October. However, the beginning of October was exceptionally dry and therefore the levels in the majority of aquifers started to decrease: 52% on 15 October (compared with 54% on 1 October).
The trends in reactive aquifers varied, depending on the amount of effective rainfall in September and the speed with which the water filtered deep into the ground. Consequently, the water levels in certain aquifers have continued to rise, even though the rate of the recharge slowed in early October. Other highly reactive aquifers, or those in which the recharge had been less marked, were already being affected by the lack of rainfall in October. Here, the levels were either stable or decreasing.
The depletion of the inertial aquifers in the Artois Basin and the Paris Basin continued through early October, since they react slowly even to significant rainfall. The recharge period finally started in the inertial aquifers in the Rhône-Saône corridor, since the total amount of rainfall in this area was more significant. The levels there have risen.
Situation observed on piezometers on 15 October 2025.
© BRGM
The groundwater situation
The situation did not change much between the reports published on 1 October and 15 October: the levels recorded at 33% of the observation points were below monthly averages, 22% were comparable with monthly norms and 45% were above average (compared with 31%, 23% and 46% in September, respectively). The lack of rainfall has not yet had a significant impact on groundwater levels.
The overall state of the aquifers remained satisfactory, ranging from close to monthly norms to moderately high. Certain reactive aquifers had moderately low levels, since there was not enough rainfall in September to produce recharge episodes: notably in the Armorican Massif and the Boulonnais, Avesnois, Berry, Adour and Gave de Pau regions. The levels of the aquifers in the Roussillon, Corbières Massif, Aude and southern Corsica remained very poor, with low to very low levels.
Forecasts
The forecasts concerning reactive aquifers remain uncertain: the trends and any changes in situations will essentially depend on how much rain falls locally and how reactive the aquifers are to rainfall. The levels could continue to drop if the lack of rainfall persists. On the other hand, recharge episodes may occur if there is enough effective rainfall.
As regards the inertial aquifers, the recharge should continue in the Rhône-Saône corridor. In the Artois Basin and the Paris Basin, the recharge should begin in November, as the vegetation becomes dormant and heavy rainfall sets in. Nonetheless, any changes in the levels of inertial aquifers should only occur slowly.
Aquifers whose levels are currently below monthly norms should continue to be closely monitored.
Groundwater situation: a new map and more frequent bulletins
The BRGM groundwater status report, which is eagerly awaited by the public every month, is being revamped. It will now be published twice a month, and the map will have a new colour scheme to make it easier to read.
As of 1 July 2025, the comparative map between the current month and the same month of the previous year will also be reissued with the new colour scheme.
Map drawn up by BRGM on 17 October 2025, based on data acquired up to 15 October 2025.
Data source: ADES (ades.eaufrance.fr) / Hydroportail (hydro.eaufrance.fr) / Background map © IGN. Data producers and contributors: APRONA, BRGM, Conseil Départemental de la Vendée, Conseil Départemental des Landes, Conseil Départemental du Lot, EPTB Vistre Vistrenque, Parc Naturel Régional des Grandes Causses, Syndicat Mixte d’Etudes et de Travaux de l’Astien (SMETA), Syndicat Mixte pour la protection et la gestion des nappes souterraines de la plaine du Roussillon (SMNPR).
This map shows the global indicators reflecting the average fluctuations of the aquifers. They are based on point indicators collected at groundwater monitoring points (by means of piezometers).
The "Aquifer levels" indicator compares the current month’s figures with those of the same months in the entire record, i.e. at least 15 years of data and sometimes up to as much as 100 years of data. It is divided into 7 classes, from the lowest level (in red) to the highest (in dark blue).
The grey areas correspond to areas without unconfined aquifers, i.e. with an impermeable or semi-permeable layer above the aquifer, and/or sectors with a very low density of measuring points. This last case primarily concerns mountainous areas with small, heterogeneous aquifers.
The "Evolution of levels" indicator reflects the variation of the water level of the past month compared to the two previous months (stable, increasing or decreasing).
These global indicators reflect general situations and trends and do not take into account possible local disparities.