This place has lots of large tanks, and various shipping points in CONUS:

http://stores.ebay.com/TANKS-MORE

I think the idea of that indoor tank is you bring it in the house THEN fill it from a hose. Here's a 300 gallon version:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3847549800

For the non-drinking purposes you describe I think I'd go for rain barrels (collect rainwater runoff from your roof). You can use that water for such purposes (plus lawn watering, etc.) regularly and cut your water consumption considerably, plus you always then have a supply on hand.

Or if you have an in-ground swimming pool...