The Water Supply Assembly (WSA) is part of the Liquid Management Section (LMS) of the Hermes Environmental Control and Life Support Subsystem (ECLSS) (see ref.  and ).The WSA has to provide pure water for drinking and food preparation (rehydratation of dry food and beverage powder) and to provide pure water for hygiene purposes (oral hygiene and towel wetting).To obtain different desired temperatures (as well as different quantities of water to be dispensed), a heating device, using electrical foils, and a cooling device, using a water/water heat exchanger have been designed with regard to the critical mass and power requirements. Two dispensers are used to fill food/beverage or hygiene (towels) containers.As part of the Hermes C1 phase, breadboard models of the heating device (heater) and of the cooling device (chiller) have been manufactured and functionally tested.This paper presents and describes the design concepts for the whole WSA and focuses on the main breadboard test results which have been obtained for the heater and for the chiller. The tests deal with thermal and hydraulic aspects as well as with the loop regulation. From these results, recommendations on the design concept optimization and on further development work are given.