Rainbarrel PSI Issues

There are some things I need to know about how water is used. Like, how much pressure (PSI) is needed to run sprinklers, appliances, faucets, etc. Also, what are some valid techniques for achieving that pressure. For example, if I put my 55 gallon rainbarrel on a tree stump, will I be able to run a sprinkler?

I found a helpful article at http://www.howstuffworks.com/water.htm, and I learned this:

• Each foot of height provides 0.43 PSI (pounds per square Inch) of pressure
• A typical municipal water supply runs at between 50 and 100 PSI
• Major appliances require at least 20 to 30 PSI

That means I would need a 45 foot tree stump!