About Private Wells, Facts for Home Buyers and Home Owners
How Private Wells Are ConstructedThere are numerous ways to construct private wells, but all safe wells have one thing in common--they must be built to tap into and deliver sanitary water.
Private Well ComponentsThe borehole, or well shaft, is lined with a solid pipe that seals out contaminants and stabilizes the hole that reaches down to the water.
The lining in the borehole is called the casing.
The wellhead is the top of the well, the part you can see at the surface. In my state, North Carolina, the driller must leave at least twelve inches of casing above the soil line, which is capped then stabilized with a concrete slab that extends at least two feet on all sides of the casing.
When we're showing houses, we sometimes see old wells with casings cut to ground level. That is no longer allowed, because when the pipe is at or near the ground it's easy for any type of excess water to flow in, bringing along bacteria, pesticides, and other contaminants.
Controlling Well Position and ConstructionPrivate wells must be positioned away from septic tanks and sewer lines. Your state or county might require that a licensed well digger construct the well.
Visit your local health department if you're not sure how well construction is regulated in your area. Even if septic tanks and wells are not controlled by that office, health department staff can usually refer you to the people who work in that profession.
No matter which type of well you have, it must be deep enough so that water comes from an aquifer, a layer of saturated soil or rock. The construction methods below are the types seen most often in my area. Your county health department or educational extension office can probably tell you more about these and other methods that might be used where you live.
Drilled WellsPercussion drilling: a weighted chisel is repeatedly dropped onto the earth, eventually forming the borehole.
Rotary drilling: a cooling solution is circulated in the hole to cool a fast-moving drill stem as it travels downward.
Driven WellA pipe-end is fitted with a sharp point and filtering screen, then driven into the earth. The pipe remains in place to deliver water to the house.
Dug WellYou've probably seen photos of old-fashioned wells with crank-down baskets--those are examples of dug wells. The large opening is lined with brick, rock, or another substance. Most were dug with a pick and shovel and are much shallower than drilled wells.
The large opening of a dug well makes it very difficult to keep contaminants out of the water.
Bored WellsBored wells are excavated with an earth auger, then lined with concrete pipes. They are the modern equivalent of a dug well.
Before a Well is Used
- Sediments and remnants that are left over after the drilling process are removed.
- The well is sanitized with chlorine, then flushed.
- The water should be analyzed for bacteria. Some health departments recommend you do another water test a few weeks after the first, to make sure bacteria levels are unchanged.
It's always a good idea to make a satisfactory water test a contingency when you're buying a home to make sure the water conforms to local pure drinking water standards. Talk to a water testing professional to find out which types of water tests are important in your area.