Denver Water says the city will be facing a drought at some point in the future and we need to be ready.
Now the agency is investigating underground water storage.
The 70-foot rig on East 64th near Picadilly Road in Adams County is part of that effort.
Denver Water is using the rig to drill into what is known as the Denver basin, a collection of sand, gravel and rock - known as aquifers - where water storage is possible.
The basin is roughly as large the state of Connecticut - stretching from Greeley to Colorado Springs and from Golden to Limon.
Right now engineers are testing the rocks to see if it would work to pump drinking water underground to save it for a time when Denver is in a drought.
Denver Water said it will know at the end of the year whether it wants to continue with the project. If so, the next step will be the creation of a pilot well to continue testing.
