cc_byNeef, Nicolas E.Zietlow, KimOtto, Siegmar2026-03-022026-03-022026https://doi.org/10.1177/21711976251412673https://hohpublica.uni-hohenheim.de/handle/123456789/18938This study investigates how a prosocial propensity, an inherent human attribute characterized by the willingness to incur personal costs for the benefit of others, functions as the foundation of water-conservation behaviour in Jordan and Germany — countries with starkly different water availability. We utilized survey data from university students and applied item response theory and linear regression. The prosocial propensity was indicated in line with previous studies via Honesty-Humility. However, against our expectations, the relationship between prosocial propensity and water-saving behaviour was not observed in Jordan ( N  = 428), a nation facing severe water scarcity. In contrast, in Germany ( N  = 540), where water is relatively abundant, our findings demonstrate a weak but clear relation between prosocial propensity and water-saving behaviour. The results suggest that a prosocial propensity manifests itself under some circumstances in water-saving behaviour but that this relation might depend on the local and cultural context. Thus, the study underscores the complexity of behaviours towards natural resources as they intersect with personality, cultural backgrounds and resource availability.engHonesty-humilityProsocial propensityEcological behaviourCross-cultural studyWater-saving behaviour300Article2026-02-20