HS10S combination water supply units integrate a check valve with test point, reverse rinsing fine filter, pressure reducing valve and shutoff valve in one appliance. They ensure a continuous supply of filtered water. The fine filter prevents the ingress of foreign bodies, for example rust particles, strands of hemp and grains of sand and thus reduces the probability of corrosion. The check valve protects the mains water system against back pressure, back flow and back syphonage of health threatening liquids. The pressure reducing valve prevents overpressure damage and reduces water consumption. Technical features of each unit also apply to the combination assembly.