A fluid reservoir for a vehicle includes a reservoir body with a sensing chamber portion, a neck portion, and a reserve chamber portion. The neck portion is connected to the sensing chamber portion and the reserve chamber portion is connected to the sensing chamber portion by the neck portion. The neck portion defines a neck portion volume that is smaller a volume defined by the sensing chamber to limit slosh in the sensing chamber when a reserve volume of fluid is present within the fluid reservoir. Windscreen washing systems and aircraft having fluid reservoirs are also described.