What sizes do water wells come in? Water well size is determined by the casing diameter and the volume of flow through sand, gravel, rock, or caves. A well is sized by the inside diameter of the finished...
A well is sized by the inside diameter of the finished product. If you say you have a four inch well, that usually means that the casing that the inside diameter of that casing is four inches. This determines the size of the pump you'll need.
The other thing that's tied to the size of the well is the flow, or how fast water can flow into the barrel. Flow is tied to the porosity of the zone, whether it's sand, a gravel bar, or a porous rock. Let's take for example a porous rock. The pores are very tiny allowing only a small amount of water to flow through them. If that porous rock is a 30 foot deep cave, it's going to flow much faster. Also, the flow is tied to the thickness of the formation. If your formation is a gravel bar that is 5 feet thick, it might flow in at 10 to 15 gallons per minute, but if that gravel bar is 50 feet thick, it might flow by several hundred gallons per minute.
How much footage multiplied by the porosity tells you how many gallons per minute a well is soaked. When somebody says "the size of the well," those are the two things they're talking about.
