Double-wall tanks prevent chemical spills without lined concrete containment, featuring a primary inner tank and secondary locked-on outer tank. Constructed of high-density crosslink or linear polyethylene with tanks from 150 to 6,550 U.S. gal. Linear polyethylene tanks are certified to NSF/ANSI Standard 61 and high-density crosslink resin tanks certified by NSF for chemical storage. Wall thickness conforms to ASTM D-1998 standards for liquid containment. Quality management system ISO 9001:2008 Certified.