Chandigarh, Aug. 29 -- City Beautiful's groundwater extraction falls in the 'safe' category but the city's aquifers are grappling with long-term decadal depletion, severe geological imbalances, and heavily dependent on rainfall for recharge, a comprehensive assessment by the Central Ground Water Board (CGWB) and the municipal corporation (MC) revealed. The report, 'Dynamic Groundwater Resources of Chandigarh-2025' states that the city's groundwater extraction stands at 67%, i.e safe. An assessment unit is classified as 'safe' when the groundwater extraction is less than or equal to 70%, according to the standardised scientific methodology used in the report. This is a major improvement since 2017, when heavy pumping and low estimated replenishment pushed the extraction to the semi-critical category at 89%. Notwithstanding the gains, the report warns that the city's seemingly secure water status is heavily dependent on artificial infrastructure and remains fragile. Natural groundwater replenishment is increasingly under siege from a changing climate and rapid urban sprawl. During the 2024-25 groundwater assessment year (June to May), Chandigarh recorded 878.3 mm rain, a 13% deficit compared to the normal annual benchmark of 1009.7 mm. Because more than 80% of the city's annual rainfall is compressed into just four monsoon months (June to September), the natural aquifer system relies on a very narrow recharge window. This seasonal concentration makes the water table highly sensitive to monsoon variability. During dry years, natural infiltration drops immediately. In fact, direct rainfall recharge dropped from 14.71 million cubic meters in 2024 to 14.17 million cubic meters in 2025. Compounding this meteorological vulnerability is Chandigarh's transition into a heavily built-up environment. The report labels paved portions of the city as "concrete jungles" where natural infiltration is severely restricted. Because paved surfaces prevent rainwater from seeping into the ground, hydrogeologists must apply a heavily reduced 30% infiltration factor when estimating rainfall recharge in these urban areas. In a surprising finding, the city's aquifers are largely being kept afloat by its own water infrastructure - or rather the shortcomings in it - instead of natural precipitation. Pipeline leakages from the urban water supply network have emerged as the single largest contributor to groundwater recharge, accounting for a massive 39% (2,070.10 hectare-metre) of the annual total. This is much higher than natural rainfall, which contributes only 27% (1,417.72 hectare-metre). Sewerage leakages also physically replenish the shallow aquifers under an ad-hoc 50% recharge calculation rule. This replenishment, however, comes at a high environmental cost: the report explicitly notes that seepages from the sewerage network contaminate groundwater resources with nitrate, threatening shallow water quality. The report highlights a severe hydrogeological imbalance between the city's deep and shallow aquifer systems. To ensure high-quality municipal drinking water, the civic body exclusively taps the deeper aquifers (40 to 450 metres below ground level). As a result, these deep reservoirs are facing severe over-extraction. In contrast, the shallow aquifers (less than 30 metres deep) are left unpumped, causing them to overflow in some locations. This has triggered a chronic waterlogging crisis in Chandigarh's western and southwestern sectors, including Maloya, Dadumajra, Palsora (Sector 40), Badheri (Sector 41), and adjoining residential areas (Sectors 39 and 49 to 56). Geologically, these southwestern sectors sit on the Older Alluvial (Sirowal) formation, a clay-rich belt characterised by low permeability. Because Chandigarh topographically slopes downward from the northeast to the southwest, groundwater naturally flows toward these southwestern sectors, where the low-permeability clay layers trap the water near the surface, keeping the water table at a shallow 3 to 10 metres below ground level. To modernise the city's supply, the MC plans to fully phase out domestic tubewells and transition entirely to piped surface water within the next 4 to 5 years. The Central Groundwater Board has issued a warning: if localised groundwater pumping is completely stopped in the clay-heavy southwestern sectors, the shallow aquifers will overflow even further, drastically worsening the waterlogging crisis in residential neighborhoods. To prevent this, the board recommends a conjunctive water-use strategy, urging the city to continue active pumping from the shallow southwestern aquifers specifically to lower and manage the water table, even as piped surface water is expanded elsewhere....