When using 4-inch wells does the well width have an effect on low-flow sampling?

There are low-flow purging and sampling devices that get as small as ¾-inch diameter. In fact, there are some companies now making mechanical bladder pumps that can fit into ½-inch monitoring wells (basically 12 mm diameter). The question has come up about larger diameters, in other words, is a 4-inch diameter too big? But, a lot of field studies are conducted in 4-inch monitoring wells. When you start getting into larger wells like 6-, 8- or 10-inch diameter casings, then it becomes an issue of the volume of water required to pump at a low rate in order to get exchange within the screens and the wells.