Hydrogeological situation on 1 August 2025
The rainfall in July hardly affected the aquifers. Depletion has been slowed by localised and intermittent recharge episodes. However, 88% of the levels continued to fall. The condition of the aquifers is deteriorating slowly and levels remain heterogeneous, ranging from very low to moderately high. The situation for the reactive aquifers in the north-east was not very favourable, as there was insufficient recharge towards the end of the winter. It was more satisfactory for reactive aquifers that have been sustained by effective rainfall in late winter and spring, and for inertial aquifers.
In August, the levels are expected to continue their downward trend. As regards reactive aquifers, the trends and developments will depend primarily on effective local rainfall and the demand for water. The storms that usually occur towards the end of summer are expected to affect only the most reactive aquifers. Even then, recharge episodes are expected to be intermittent, and of low intensity. The condition of inertial aquifers is not likely to change much in the next few weeks, except in areas with particularly intensive demand for groundwater abstraction. The situation will need to be closely monitored in aquifers which currently have levels that are below the monthly averages, as well as in areas where demand for groundwater is particularly high.
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 of aquifer levels in mainland France on 1 August 2025.
© BRGM
Evolution of the trends observed on piezometers from August 2024 to July 2025.
© BRGM
Trends
The depletion period began very early, from February onwards, in the reactive aquifers over much of the north of France. The depletion then became apparent in the inertial Artois and Paris Basin aquifers during the spring. It set in between April and May in aquifers in the south of France and in Corsica. From May onwards, the rainfall was no longer effective in generating recharge episodes. Levels then remained low in May and June.
In July 2025, 88% of levels were down (compared to 87% in June).
All the aquifers are currently being depleted, as rainfall has had little effect on them. This is common for this time of year, as summer rainfall only seeps into the ground a little. On the one hand, stormy weather favours run-off instead of infiltration into the ground. On the other hand, infiltrated rainfall moistens the soil and is mostly taken up by vegetation.
However, there was plenty of rain in July. Locally, it managed to infiltrate deeply and generate occasional recharge episodes. These inflows have reduced the rate at which reactive aquifers are drained under areas that receive a lot of rain (the northern half of France, along the Mediterranean coastline and Corsica). The rainfall has led to more or less significant abstraction, particularly for irrigation and tourism, thus easing the demand on groundwater.
In the case of inertial aquifers and lightly irrigated areas with reactive aquifers, depletion is continuing. The fall in levels is locally intensified by groundwater abstraction for irrigation.
Comparison between 1 August 2024 and 1 August 2025
Map of France showing the state of the aquifers on 1 August 2024 (left) and 1 August 2025 (right).
© BRGM
Evolution of the situation observed on piezometers from August 2024 to July 2025.
© BRGM
Aquifer situation
Levels were particularly high during the low-water period in October 2024. They then varied over the autumn and winter depending on the intensity of recharging episodes. The overall situation has gradually deteriorated since February, due to a persistent lack of rainfall over a large part of northern France, which spread to the south between April and May.
On the whole the states of aquifers differed in July: the levels recorded at 44% of the observation points were below monthly averages, 24% were comparable and 32% were above average (compared, respectively, with 39%, 26% and 35% in June).
The situation was much more satisfactory in July 2024, with 70% of levels being above monthly averages, due to abundant recharge in 2023-2024 and strong inflows from rainfall in spring 2024. The situation is better in 2025 for the highly inertial aquifers of Beauce and Sundgau (southern Alsace) and for a few reactive aquifers (in the Corbières massif, Hérault and Orb valleys and Corsica).
In July 2025, the situation remained generally stable compared with June. Aquifer levels are improving slightly in the reactive aquifers in the north-east of the Armorican Massif and Corsica, which have benefited from rainfall. They are dropping in inertial aquifers, which are not very sensitive to recent weather conditions, and in reactive aquifers from the Aquitaine Basin to the Jura area.
Inertial aquifers
The state of the inertial aquifers remained satisfactory overall in July, with moderately low to moderately high indicators.
In the Artois area and the Paris Basin, levels were mostly moderately high. A few high to very high levels were measured in the western part of the Beauce. The less inertial aquifers of the Artois coast and the eastern and southern edges of the Paris Basin are more sensitive to the recharge deficits recorded in late winter and spring. Their levels are moderately low to comparable to monthly averages.
Groundwater levels in the Sundgau (southern Alsace) and the Rhône-Saône corridor are generally comparable with normal levels. Certain situations varied locally, with levels ranging from low to high.
Reactive aquifers
The condition of reactive aquifers depends on the total amount of rainfall in recent weeks and the responsiveness of the aquifers considered.
A lack of rainfall in late winter and spring had a major impact on reactive aquifers in the north (Boulonnais and Avesnois), the Grand-Est, the Jura and the northern two-thirds of the Massif Central. The levels are unsatisfactory, from moderately low to low. A few very low levels were measured in the Massif Central basement aquifers.
For the Armorican Massif, the Aquitaine Basin, the Mediterranean coastline areas and Corsica, the levels are more satisfactory, ranging from moderately low to moderately high. The heterogeneous situations can be explained by the local rainfall accumulations infiltrated during the spring, by inflows from rain in July and by the varying demand for water abstraction, depending on the location. Effective rainfall in July boosted aquifer levels in the Massif Armoricain, along the Mediterranean coastline and in Corsica. Aquifer levels remained stable or even improved in Corsica. On the other hand, there was a lack of rainfall in the Aquitaine Basin, and the situation deteriorated between June and July.
Finally, water levels are low to very low in the Aude valley, the Corbières massif and the Roussillon plain. Precipitation in July recharged the most reactive aquifers (in the Corbières in particular), and reduced groundwater abstraction (for irrigation and watering).
Aquifers with surplus water
Several aquifers were found to have a surplus, with moderately high levels compared with the levels recorded for July in previous years:
- The levels of inertial aquifers in the west and south of the Paris Basin are still moderately high due to the surplus recharges in 2023-2024 and 2024-2025;
- Levels in the alluvial aquifers of the upper Garonne and its main tributaries remain moderately high;
- The level of the Astien sands aquifer at Valras-Agde is again higher than the monthly averages, since careful management of abstractions has reduced the demand on groundwater;
- Excess rainfall in July helped to improve the condition of the aquifers along the Corsican coast and levels are becoming moderately high.
Aquifers with low water levels
The situation is unfavourable in several aquifers, with low to very low levels compared to those recorded for July in previous years:
- Levels in the reactive aquifers of the Jurassic limestone formations of the Boulonnais, Lorraine and Côte-des-Bars are low, due to a lack of effective rainfall in late winter and spring;
- Levels of the basement aquifers in the north-east of the Massif Central, the alluvium and tertiary basins of the Limagne and volcanic formations are now very low;
- Groundwater levels in the Roussillon multi-layer aquifer, the karst limestone formations of the Corbières massif and the alluvial deposits of the Aude are low to very low.
Key figures
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88.00%of levels decreased
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32.00%of levels were above monthly averages
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44.00%of levels were below monthly averages
Forecasts
The Météo France seasonal forecasts for August, September and October 2025, higher temperatures are expected across the whole of France. No clear rainfall scenario has emerged.
The high temperatures forecast by Météo-France are likely to contribute to an increase in the water requirements of vegetation and in water abstraction (irrigation, leisure activities and tourism). Given the lack of sufficient rain in August, the ground is much drier and demand for water could be high. Significant demands on groundwater could trigger downward trends depending on the location in question.
Seasonal forecasts for inertial aquifers
As regards the inertial aquifers (Artois, Paris Basin, Sundgau, Rhône-Saône corridor), no recharge episode is likely to be observed before vegetation becomes dormant and before there is significant rainfall, i.e. before mid-autumn or early winter. However, the rate of depletion could be accelerated by abstractions, particularly for irrigation. In the Artois and Paris basins, the excess rainfall in July should, however, limit irrigation needs and thus ease the demand for groundwater.
The situation is likely to remain stable or gradually deteriorate until the low-water period arrives. Low-water levels should remain above normal for the most inertial aquifers in the Artois and Paris Basin. The aquifers in the Rhône-Saône corridor are expected to remain close to normal, but could reach below-normal levels later with the low-water period being later as well.
Seasonal forecasts for reactive aquifers
As regards reactive aquifers, the trends and developments over the next few weeks will depend primarily on effective local rainfall and the demand for groundwater.
Depletion is expected to continue until the autumn and the onset of significant rainfall. The storms that usually occur towards the end of summer are expected to affect only the most reactive aquifers. Recharge episodes are expected to be intermittent, however, and not very intense.
The situation is likely to remain stable or even improve where rainfall is sufficient. The situation is likely to deteriorate rapidly for aquifers that do not benefit from small recharge events and for those that are strongly affected by abstraction. Barring exceptional rainfall episodes, low water levels in 2025 should generally be below monthly averages, but without dropping to those of 2022 and 2023.
The evolution of aquifers in poor condition in July will have to be carefully monitored, i.e. in the Boulonnais, Avesnois, Grand-Est, Jura and northern two-thirds of the Massif Central. Finally, the forecasts for the coming months remain highly pessimistic for aquifers in the Roussillon plain, the Corbières massif and the Aude valley.
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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 August 2025, based on data acquired up to 31 July 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.