The guzzler is quite a useful tool in a waterless stricken area. This facility can store around 500 gallons of water underground to help get the wildlife through the dry months, until the wet weather returns.
What the guzzler does is catch any and all of the moisture as it falls to the ground. The moisture whether it be rain or snow, lands on the collectors... rain will roll down the collectors and fall into the tank below... snow will land on the collectors and then as it slowly starts to melt, it will roll down the collector and fall into the tank below.
The lid covering the tank, is designed so that even the smallest of wildlife may fallow the water line down a ramp as the water is consumed. The ramp is etched in such a way that all the small wildlife is able to have traction to get back out without being hurt. The lid is also designed so that even the very small wildlife cannot get into the water storage tank. (tight fit)
You may see different construction styles of the guzzler while you're in the field. The end result is the same. The object is to erect the most possible surface for the rain or snow to hit, and the travel down the collectors (roofing) to the center of guzzler. There should only be an inch or less between the two collectors to slow down the evaporation that may take place.
Depending on where you are at in North Central Washington, you might see some guzzler with fences around them and some with no fence. The fence has been placed there to keep the Elk and Cattle from stepping on the lid and breaking through. Deer and Bighorn Sheep have not been a problem... thus far.
Bottom line is that it collects all of the moisture that nature gives it, and stores it during the dry months for wildlife to use.