Purenex PRO 3.2  Reverse Osmosis Water Storage Pressure Tank Best pressure tank on the market, designed to last 5+ years PAE # RO-132 NSF and CE certified tank FDA approved bladder, food grade, no rubber smell, no plastic smell, stainless steel connection on top 4 gallons outside volume, holds 3. 2 gallons of water Pre-charge at about 5-7 psi