The groundwater situation deteriorated due to the lack of effective rainfall in June and the increased demand on water resources for various purposes
As in the previous month, the depletion of aquifers continued across the whole of France, due to the lack of effective rainfall in June and the increase in groundwater abstraction. Levels dropped in 93% of the aquifers, with only 46% of observation points either above or in line with monthly norms. The situation was worse than on 1 July 2025 (when 58% of observation points were either in line with or above monthly norms).
The overall groundwater situation deteriorated, with 54% of observation points below monthly norms. The depletion of aquifers picked up pace. The most responsive aquifers, or those which had only benefited from a moderate recharge, were well below normal monthly levels.
There were contrasting levels across the country. Low levels were observed in the basement aquifers in the Limousin region and some of the aquifers in the Grand-Est region, whereas levels remained high in the aquifer in the Vistrenque basin, from Astien to Agde and the alluvial aquifers in the Roussillon plain, as well as in the lower Rhône and the upper Garonne basins and the limestone aquifers in the Touraine, Beauce and Armagnac regions.
The responsive aquifers whose levels remained above monthly averages can expect to maintain satisfactory levels over the next three months. However, it is difficult to know how the summer rainfall will be distributed across France and whether it will be sufficient to re-humidify the soil and thus reduce the amount of groundwater that needs to be abstracted for various uses, particularly agriculture. The outlook for the longer term therefore remains uncertain.
Map of aquifer levels in mainland France on 1 July 2026.
© BRGM
Evolution of the trends observed on piezometers from June 2025 to June 2026.
© BRGM
Trends
The groundwater depletion continued in June. Generally speaking, the piezometric levels of the aquifers fell across most of the country. This can be explained by the lack of effective rainfall across the whole country since May, with a particularly marked period of drought and high temperatures in the month of June.
The data collected in June 2026 showed that depletion was in progress at 93% of the observation points, reflected by decreasing groundwater levels. Levels were stable at 5% of the observation points and only 2% showed rising levels. The degree of depletion appears to be greater than in June 2025.
Aquifers with slow response times
In June 2026, the levels continued to decrease in aquifers with very slow response times. This was notably the case for the limestone aquifers in the Beauce, Artois and Normandy regions and in the aquifers in the Lutetian formations and Ypresian sands in the Paris Basin. It was also the case in the aquifers in the formations of the Bresse and Dombes regions, and in the fluvio-glacial formations of eastern Lyon and Dauphiné.
The situation in other aquifers, whose levels had stabilised, remained the same. This was the case in the aquifers in the Sundgau gravel formations and in the Savoie foothills.
Aquifers with quick response times
Levels decreased in all these aquifers. This is normal for the period, since very little of the rain that falls during storms (which are often violent, with heavy rain) filters down into the ground. In addition, high temperatures encouraged evapotranspiration and increased plant water requirements. Water abstractions for irrigation and tourism accelerated the fall in levels in certain areas.
Comparison between 1 july 2025 and 1 july 2026
Map of France showing the state of the aquifers on 1 July 2025 (left) and 1 July 2026 (right).
© BRGM
Evolution of the situation observed on piezometers from June 2025 to June 2026.
© BRGM
Overall groundwater situation
The situation deteriorated during June 2026, due to a lack of rainfall, high temperatures and increased groundwater abstraction.
At the end of June, only 46% of observation points had satisfactory groundwater levels, which were slightly above or around monthly norms. A total of 54% of observation points were below normal. More specifically, 22% of observation points were above normal, 24% were comparable with monthly norms and 54% were below normal (compared with 30%, 28% and 42% respectively at the end of May).
The current situation appears worse than that observed at the end of June 2025, when 32% of levels were above monthly norms, 26% were comparable with monthly averages and 42% were below.
Aquifers with slow response times
There were contrasting levels across the country in aquifers with extremely slow response times.
Certain aquifers had moderately high levels in relation to monthly norms, namely the aquifers in the limestone formations of the Beauce and Armagnac regions.
The Lutetian limestone and Ypresian sand aquifers in the north of the Paris Basin, the chalk aquifers in the Artois region and those in the fluvio-glacial alluvial formations of Dauphiné had moderately low levels for the season.
The other aquifers with slow response times had levels close to monthly averages.
It should be noted that significant localised differences were observed within these aquifer systems.
Aquifers with quick response times
The situation in highly responsive aquifers also varied across the country.
Some had moderately low levels, for example the Jurassic aquifers in the south-eastern part of the Paris Basin, the aquifers in the karst formations of the Jura and basement formations of Cotentin, western Brittany, Morvan and in the Massif Central. This was also the case in the limestone formations of the Charentes and the alluvial aquifers in the northern Alsace plain, the Adour and the Gave de Pau river basins and the upper Garonne, as well as in the aquifers in Corsica.
Low levels were recorded in the Jurassic limestone, sandstone and Triassic limestone formations of the Vosges and Lorraine regions, and in the limestone aquifers of the Côte des Bars. This was also the case in the aquifers in the Limagne plain and in the karst limestone formations of the Causses du Quercy, as well as in the basement aquifers of the Limousin region.
Levels remained moderately high in the chalk aquifers in Touraine, the Jurassic limestone aquifers in Vienne and in the sand aquifers of the Valras-Agde region, as well as in the alluvial aquifers of the upper Garonne, the Roussillon plain and the lower Rhône valley. Levels remained very high in the aquifer in the formations of the Vistrenque basin. Levels were around normal in the other responsive aquifers around the country.
It should be noted that significant localised differences were observed within these aquifer systems.
Changes in the groundwater situation from summer 2022 to summer 2026
The groundwater situation from 1 July 2022 to 1 July 2026.
In 2022 and 2023, the low groundwater levels were due to an insufficient recharge during the autumn-winter period and a dry spring. On 1 July 2024 however, groundwater levels were exceptionally high due to an above-average recharge and plenty of spring rainfall. The situation on 1 July 2025 was affected by a dry period between the end of winter and spring.
Finally, the variable situation observed on 1 July 2026 can be explained by the fact there was a good recharge across three quarters of the south west of France, followed by a very dry spring.
The situation in 2026 is significantly less worrying than in 2022 (except in the Massif Central) and considerably better than in 2023, although worse than in 2025, particularly in the North, North-West and Limousin regions.
© BRGM
Key figures
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93.00%of levels decreased
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22.00%of levels were above monthly averages
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54.00%of levels were below monthly averages
Forecasts
Météo-France's seasonal forecasts for the period from July to September 2026 indicate an increased likelihood of above-normal temperatures across the country. As regards rainfall patterns, Météo France predicts a one-in-two chance of drier conditions in northern France.
The water required by plants, due to higher temperatures, and increased water abstraction will accelerate the depletion of groundwater in almost all aquifers.
Aquifers with slow response times
The levels in less-responsive aquifers depend on the levels reached during the previous low-water period and on the total amount of effective rainfall during the entire recharge period.
Only the aquifers in the Sundgau region and in the fluvio-glacial formations of the Savoie foothills have stable levels. In the other aquifers, whose groundwater levels are already falling, the downward trend will continue until the autumn.
However, the outlook for the summer of 2026 remains uncertain. Piezometric levels will certainly be lower than those observed in 2025, due to a less abundant recharge in 2025-2026.
Aquifers with quick response times
The lack of effective rainfall in June resulted in the continued depletion of responsive aquifers. Nevertheless, the seasonal forecasts remain positive for the responsive aquifers that currently have high to very high levels.
As regards the other responsive aquifers, in which levels are currently around or slightly below monthly norms, the outlook remains uncertain and will depend on summer rainfall. If there is sufficient rain this could re-humidify the soil and reduce the need to pump water from aquifers for different uses (notably drinking water and agricultural irrigation).
Highly responsive aquifers are sensitive to prolonged and intense droughts. This is the case with the basement aquifers in the Limousin region, where the situation could become worrying if the dry spell continues.
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State of groundwater: monitoring by BRGM
Groundwater is a widely used resource: in metropolitan France, it accounts for nearly two-thirds of drinking water consumption and more than one-third of agricultural water consumption. It is also widely used in the industrial sector. Groundwater tables depend on cyclical recharges.
BRGM monitors groundwater levels and quality in mainland France. Discover the actions carried out by the French geological survey and the resources and databases available on groundwater in France.
Aquifer recharge: 3 questions to provide a better understanding of the process
How do aquifers fill up and how do they empty?
Groundwater levels vary throughout the year, from high levels in winter (when vegetation does not absorb rainwater) to low levels in summer (the traditional depletion period).
The fate of rainfall varies greatly depending on the time of year and the condition of the ground surface on which it falls. Usually, the groundwater-recharge period takes place from early autumn (September-October) to early spring (March-April), a six-month period during which vegetation is dormant (with low evapotranspiration) and rainfall is generally more abundant. If the winter is dry, groundwater recharge is very low.
From spring through summer, rising temperatures coupled with the regrowth of vegetation and thus increased evapotranspiration, limit the infiltration of rainfall into aquifers. Between May and October, unless there are exceptional rainfall episodes, aquifer depletion usually continues and levels will keep decreasing until the autumn.
Why do some aquifers recharge faster than others?
Groundwater flows at different rates depending on the porosity (percentage of gaps/cracks in the rock) and permeability (capacity to allow water to circulate, i.e. interconnectivity between these gaps/cracks) of the aquifers. The larger the gaps and the more interconnected they are, the faster the water will flow, for both refilling and depletion.
It takes a given volume of water different periods of time to travel the same distance, depending on the kind of rock formation:
- a few years in a porous formation,
- a few months in a cracked formation,
- and a few days, or even a few hours, in a karst formation.
Inertial and reactive aquifers: what are they?
The impact of the winter recharge varies according to the cyclic nature of the aquifer, i.e., its reactivity to rainfall infiltration.
We refer to aquifers that are:
- reactive (when they are composed of sand, gravel, karst limestone or weathered granite formations). These aquifers are characterised by their rapid reaction times: they can recharge during heavy summer rainfall, but are also highly sensitive to drought. Their levels can therefore vary very quickly over the course of the same season.
- inertial (when composed of chalk, non-karst limestone, sandstone formations). Their reaction times are slow. They can have multi-annual cycles, meaning that they require a long period to recharge or empty.
Cyclicity of aquifers in mainland France.
© BRGM
Map drawn up by BRGM on 6 July 2026, based on data acquired up to 30 June 2026.
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.