While municipalities rely on city water to provide for their residents, many rural areas still rely on local wells to provide all the water necessary for everyday use. Drilling a new well is a complicated process that requires many steps. (Learn more in Horizontal Directional Drilling: 7 Key Facts to Know.)
What to Know Before Drilling
Locating an underground water resource is not as hit-and-miss as one might think. As rain falls, water accumulates in a zone of saturation better known as an aquifer. It's this layer that owners tap to create a well for human consumption. However, the lay person may not be as adept at locating the best zones for their well construction. A trained geologist or engineer can use aerial photographs to determine the best location, generally a fractured rock zone.
Before any drilling begins, it's essential to check with local government officials to determine what the required permits are. Some areas may require surveys or special licenses before drilling begins. A licensed driller can help you obtain the proper permits before you start.
When planning a well, an experienced local contractor can help determine if there is enough water to satisfy your needs. "Enough" is defined as a sufficient quality to complete everyday tasks like cooking, drinking, and plumbing. It also includes seasonal uses for watering the lawn, swimming pools and washing a car. Owners who farm or keep farm animals there need to be an adequate amount to irrigate crops and water the animals. Conservatively, everyday use requires at least 150 to 300 gallons per day for two to four people in the family.
You must consider other factors to determine if there is enough water. One element is flow rate or the continuous rate of yield. Additionally, the size of the well, including the diameter and depth, is an issue. Finally, the level of water when no water is pumped out is a contributing factor.
Before drilling a well, there are location considerations. The wellhead must maintain a minimum distance from contaminants. At a minimum, the location cannot be closer than 200 ft from a cesspool, 50 ft from a filter bed, septic tank or tile sewer. The wellhead must be more than 10 ft from an iron sewer and two feet from the pumphouse floor drain. Additionally, the well may not be closer than five feet from the property boundary and 20 ft from the outer edge of any road. Landfills and garbage dumps must be more than 200 ft away from the well.
As water well drilling is a complicated process, there are different tools needed for the job. (Learn more in A Complete Guide to the Usage and History of Drill Bits and Tooling.) A skilled, trained driller is definitely required to complete the task; the specific tools will vary depending on the type of work completed.
Air Rotary Drilling
An air rotary drill uses a rotary drill bit to cut into the ground. This system uses compressed air to remove the cuttings, pushing them out of the newly drilled hole and out through the top. While it is an ideal choice, as there are no fluids left in the well, it does have limitations when dealing with hard rock formations. Drillers may use air rotary drilling in conjunction with another type of drilling to compensate.
Mud Rotary Drilling
The mud rotary drilling method is very similar to air rotary drilling, as both use a rotary bit to bore into the ground. Unlike air drilling, removing the cuttings is accomplished using a drilling fluid know as mud. The mud goes into the hole and pushes the bits to the surface. The mud also cools the bit and lubricates other moving components. Generally, workers use this tool in areas where there are unstable rock formations.
While most licensed drillers stick to the traditional methods of air or mud rotary drills, some choose to use a combination of the two with foam drilling. Instead of using mud to remove the cutting, this method uses a foam additive. It offers the benefits of not having drilling fluid in the hole coupled with the faster cutting removal. The downside is that the foam may prove difficult to contain and might be costly.
In addition to the drill itself, many companies use a good casing to help stabilize the new well and prevent contamination for the surrounding soil. Finally, workers install a pumping mechanism to propel water to the household water system. The type of pump depends on the depth of the well, as some only work at a depth of 30 ft while others work in depths over 100 ft.
How to Drill a Well
After carefully planning, it's time for your licensed driller to come in and complete the project. The first step is drilling the physical well. This requires a complicated rig equipped with an auger bit. Depending on the soil conditions, your contractor will determine which method is best and may use a combination of the mud and air drilling methods. (Learn more in 7 Types of Trenchless Rehabilitation Methods and How They Are Used.) Generally, the drilling company will drill below the water table to ensure an ample supply.
Once workers complete the drill, they install a casing. Casings are long steel or plastic pipes used to line the new well. They have a dual purpose of providing integrity to the newly drilled well walls and helping to prevent contamination from the surrounding soil. The casing also insulates the well and to avoid freezing in the winter time.
After the casing is in place, workers fill the two-inch gap, known as the annulus, with gravel. Gravel doesn't go all the way to the top, however. The top 20 ft of the annulus is concrete which is used to help prevent surface contaminants from getting into the well.
Often, workers place a screen and gravel at the bottom of the well. Gravel works as a natural filtration system to prevent contaminants from making their way into the home’s water supply. Workers placed a pump and connected to the home’s water system. Many of these pumps contain filters which prevent large particles from being drawn into the pump.
Knowing the limitations of your area as well as where to place the well is only a small part of the process. Soil conditions dictate what type of boring tool to use as well as how far down your contractor needs to go to provide an adequate supply.