Perhaps consider using a Watersafe!

They make three sizes, a Watersafe Mini, 5 gallon sink/stand alone tank, Watersafe, 65 gallon bath tank, and a Watersafe Heavy Duty, 55 gallon stand alone tank.

All are easily filled, have closures, and outlet handpumps, but best of all, they pack small till you need them.

I saw these about a year ago and thought they were a sensible addition to a household kit.

Watersafe