Depends on which direction you are coming. You might try the Alligator Farm in Mosca. Lots of places to fill in Alamosa; the gas station-convenience store in Villa Grove; and Rainbow Market in South Fork or city park in Del Norte.

The Great Sand Dunes National Park let us fill our water tank at the camp ground, but the fellows at the entrance gate weren’t thrilled about it.

At the visitors center in the National Park we used our supply of 1 gal water jugs and filled them. We asked first and they were fine with it.