In NM, it is technically possible to catch close to 80% losing some to evaporation if it is hot. I have a friend who does it and reports his gallons on a monthly basis.
We are in the high desert and our average rainfall per year is only 8-9 inches. In 2011, we were below normal for the state and way below normal in ABQ with less than 5 inches and they mostly came all at one time. We joke about a 5 inch rain..meaning the drops were 5 inches apart.
We have a flat roof (tar and gravel) on an adobe home with 3000SF total roof area and canales. The canales (basically wooden spouts with metal liners) are used in this area to drain the roof.
We put 55 gallon plastic barrels retrofitted with a spigot and mesh top under each canale (5). We could have had more barrels and hooked them up in a series so one overflowed into another but have not done that yet.
So, when a hard rain comes, we go out and open the spigot with a hose attached (so the barrels don't overflow) which goes to our fruit trees as they need deeper watering. If it is a lighter rain that does not overflow the barrels, we have more latitude to use when we need to.
Ideally, I would love to have an in-ground cistern with a purification system. With our water crisis, the city is a little more lenient about allowing such systems (even grey and black water catchment) if protocols are followed. Many of the newer high end "green" homes have such systems included for landscape watering.
As mentioned, in Taos there are homes near the gorge where water is over 800' down IF you can find it. My daughter got an estimate on a property there and the well could have been $80-100K. I discouraged her from buying the property but she was very comfortable collecting water with a cistern as so many do in that area. They get bottled water for drinking and as a backup. Taos has a unique culture and these homes have marketability. Dennis Weaver's old home.
http://www.premiersystems.com/earthship/
An off the grid home in ABQ but with a well.
http://www.greenhomesforsale.com/listing.php?id=19285