I have a 30 gallon tank in my truck I use for house washes and fill it up 3/4 the way with SH and the rest water and add some SC and go wash houses. I get about 6 houses out of it so it does not stay in there long but you can always add a refresher of SH as you go. I used to use buckets but a 30 gal square tank takes up about the same space a 4 buckets. Buckets can tip over and leak or spill out, plus you get crap on you sometimes filling a bucket.
