You can find technical-grade distilled water in 5-gallon sizes on Amazon or through industrial suppliers like ChemWorld, though these are often more expensive ($60+). Go to product viewer dialog for this item. Pure Life Distilled Water 5 Gallon Jug
For direct purchase, several major retailers and specialized merchants offer 5-gallon distilled options: where to buy 5 gallon jugs of distilled water
Frequently carries Primo 5-Gallon Water , though availability of the distilled variety specifically varies by store. You can find technical-grade distilled water in 5-gallon