The title compound, C18H19Cl2NO4 center dot C6H12N2 center dot H2O, is a cocrystal hydrate containing the active pharmaceutical ingredient felodipine and diazabicyclo[2.2.2]octane (DABCO). The DABCO and water molecules are linked through O-H center dot center dot center dot N hydrogen bonds into chains around 2(1) screw axes, while the felodipine molecules form N-H center dot center dot center dot O hydrogen bonds to the water molecules. The felodipine molecules adopt centrosymmetric back-to-back arrangements that are similar to those present in all of its four reported polymorphs. The dichlorophenyl rings also form pi-stacking interactions. The inclusion of water molecules in the cocrystal, rather than formation of N-H center dot center dot center dot N hydrogen bonds between felodipine and DABCO, may be associated with steric hindrance that would arise between DABCO and the methyl groups of felodipine if they were directly involved in hydrogen bonding.