Those things cost you 20 to 25 dollars a pop. Last only a short time. save for an RO unit. some on ebay are really good and cheap. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=20756&item=2395926188&rd=1 For the price it is not bad.... I like the clear filter cartridges so I can see my DI resin change and this does not have them... but if you test it with a TDS meter all should be ok.