Reverse Osmosis Replacement Pre/Post Water Filters Reduces Numerous Contaminants The Whirlpool UltraEase reverse osmosis replacement pre/post filter (WHEERF) should be replaced every 6 months to keep the system working efficiently and to ensure the highest quality water is available for your family. This system is NSF certified and built in the USA. All Whirlpool under sink drinking water systems employ patented UltraEase Technology allowing for easy filter change with no hassle or mess. This system also includes an EZ-Change Indicator Light that notifies you when it is time to change filters. Systems WHAROS5, WHAPSRO and WHER25 Whirlpool Reverse Osmosis Systems reduce or remove many contaminants including lead, cysts, dissolved solids, chlorine taste and odor, sediment, arsenic (pentavalent), barium, cadmium, chromium (vl), chromium (III), copper, nitrate, nitrite, radium, selenium, fluoride, turbidity, ammonium, bicarbonate, bromide, chloride, magnesium, sodium, sulfide, tannin, zinc and other chemicals. Filter Life (Gallons): 270.