I use bottled water and sanitize my large french press. Normally I go with a half pound of grounds and add water. Stir very well to make sure all the grounds are good and wet. I let mine for 18 hours and press. I get about 24-30oz out of it. I add at kegging to taste, but it's normally pretty close to all of the concentrate.
Leftover concentrate gets mixed 1:1 with half and half. It's really tasty.