purelyH20 makes high quality stuff...I bought a 100gpd optima with flush kit, pressure guage, and auto shutoff for quite a bit less than $195 back when Bryan was doing a special on a group order from MAAST. I am getting 0TDS w/out the second carbon filter for cloramines, but I did use up the D.I. resin in about 150 gallons. I'd suggest getting a refillable D.I. cartridge and buying bulk resin; it's way cheaper.