On my website: http://mysite.verizon.net/vzeegf8v/inde ... istern.htm
I have the dimensions that translate to gallons for a cistern.
You can make a concealed cistern rather easily by taking a small flower garden and using make 4 small walls. Let's say for this exercise it's 5' long, 2' wide, and you make it 3' tall. That should hold about 450 gallons of water. Create a false top using plywood (covered with thick plastic sheeting) or whatever you have around and put soil on top. Plant annuals and you'll have a concealed cistern. Looks good and functional!