Any measured He concentration in a particular reservoir such as in whole rocks, in individual mineral grains, in porewater or groundwater samples or in a gas phase, represents a history of production, accumulation and transport of helium in the subsurface. An evaluation of possible helium transport mechanisms in a hydrogeological study leads to a diffusive-advective transport model. Based on estimated block sizes and transport parameters, the time required for the measured porewater He concentrations to accumulate can be calculated and taken to represent a minimum porewater residence time.