Water Sources: Drilled Well
Overview
In areas where groundwater is available, a drilled well can be the preferred source of reliable, high-quality water. About 50% of Kansas is covered by aquifers that reliably yield enough water to supply a well. Where major aquifers are not found, small local aquifers may provide adequate water for a low-output well.
Advantages
- No evaporation or seepage losses.
- Soil provides good protection from surface water contamination.
- May be located near where water is needed.
- Not subject to freezing.
- Water quality is usually consistent; changes in quality tend to occur slowly.
- Has a long, useful life, especially when properly maintained and protected.
Limitations
- Extended drought may result in lower water levels and discharge rates, or the well going dry.
- In some areas, groundwater is located quite deep, making the well prohibitively expensive.
- Deep wells may have brackish water in many areas of Kansas.
- Test holes, abandoned wells, or careless surface activities have polluted groundwater in some areas.
- Groundwater is constantly moving through the aquifer, causing changes in water quality.
- Much of east-central and southern Kansas lacks groundwater aquifers.
Design Consideration
Kansas well drillers are licensed by Kansas Department of Health and Environment and must use well components that meet state construction standards.
Wells should be located upslope and away from contamination sources and activities that may affect water quality. Slope the ground surface away from the well to prevent water from ponding within 50 feet of the well. The slope should be at least 6 inches in the first 20 feet from the well to ensure drainage. Fencing or a managed area around the well can offer protection from careless actions or contaminants that might harm the water quality.
A watertight casing should extend at least 1 foot above the ground, and the casing should be tightly capped or plugged with a sanitary seal to prevent the entry of surface water that may contain pollutants. A screened vent installed in the cap allows air movement into the well, preventing casing collapse.
If the site is prone to flooding, the casing should extend 1 foot above the highest expected flood level. The casing must be watertight its entire length from the top of the casing to the water intake screen below the water table. No holes are allowed in the casing except for an approved pitless adapter, which must be sealed to the casing.
An approved grout is used to seal between the borehole and the casing from the surface to 5 feet into the first clay or shale confining layer or 20 feet below the surface, whichever is greater. The grout must be placed adjacent to all confining layers to separate water bearing layers. Bentonite clay, neat cement, and cement-water slurries are all approved grouts.
An approved pitless adapter is installed where a subsurface pipe joins the well casing when there is no well house, enabling a water-tight connection below frost level.
Maintenance is essential to ensure the well continues to meet all location and construction standards. Components should be check annually and cleaned and disinfected after inspection or anytime the well casing is opened (see K-State Research and Extension publication, Shock Chlorination for Private Water Systems, MF911). Test the water after maintenance activities to confirm the water remains uncontaminated.
Well drilling is regulated by KDHE Bureau of Water Geology section. Wells should be drilled by a licensed waterwell contractor abiding by state waterwell regulations. Some counties or regional jurisdictions may have additional well drilling regulations and may require permits. State law requires that abandoned water wells should be plugged.
This practice may require permits. Please read the permit section of this handbook.
