The geochemical signature of many speleothems used for reconstruction of past continental climates is af-fected by kinetic isotope fractionation. This limits quanti-tative paleoclimate reconstruction and, in cases where the kinetic fractionation varies with time, also affects relative paleoclimate interpretations. In carbonate archive research, clumped isotope thermometry is typically used as proxy for absolute temperatures. In the case of speleothems, however, clumped isotopes provide a sensitive indicator for disequilib-rium effects. The extent of kinetic fractionation co-varies in 47 and δ 18 O so that it can be used to account for disequilib-rium in δ 18 O and to extract the past drip-water composition. Here we apply this approach to stalagmites from Bunker Cave (Germany) and calculate drip-water δ 18 O w values for the Eemian, MIS3, and the Holocene, relying on indepen-dent temperature estimates and accounting for disequilib-rium. Applying the co-variation method to modern calcite precipitates yields drip-water δ 18 O w values in agreement with modern cave drip-water δ 18 O w of −7.9 ± 0.3 ‰, de-spite large and variable disequilibrium effects in both cal-cite δ 18 O c and 47 . Reconstructed paleo-drip-water δ 18 O w values are lower during colder periods (e.g., MIS3: −8.6 ± 0.4 ‰ and the early Holocene at 11 ka: −9.7 ± 0.2 ‰) and show higher values during warmer climatic periods (e.g., the Eemian: −7.6 ± 0.2 ‰ and the Holocene Climatic Optimum: −7.2 ± 0.3 ‰). This new approach offers a unique possibil-ity for quantitative climate reconstruction including the as-sessment of past hydrological conditions while accounting for disequilibrium effects.