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Frequently Asked Questions About Groundwater and Water Wells in Kentucky

 Where can I find general water information for Kentucky?

The KGS web site has many sources of information regarding groundwater and surface water in Kentucky. General information on water, water-related research at KGS and access to Kentucky groundwater data (wells, springs, water quality) can be found at <>. A quick way to locate water-related publications is through the KGS online list of publications, located at <>.

I would like to drill a water well on my property. How do I go about it?

We have several links on our web site that might be of assistance in determining the possibility of obtaining groundwater at your site. KGS has recently published a set of groundwater resource reports by county, available online at < html> (use the drop-down menu to select your county). Each report has from 10 to 26 pages in pdf format on the hydrology, geology, and water supply of that county.

The United States Geological Survey (USGS) in cooperation with the Kentucky Geological Survey completed a set of maps in the 1960’s called “hydrologic atlases”, which are designed to assist in locating groundwater. These maps have been scanned and are available online at < rary/USGSHA. html>. They cover from three to ten counties each, and are in pdf format. These are 3 maps each - one for general geology, one for availability of groundwater and one for a lithologic unit column (which describes the rocks). Check the “availability of groundwater” map for older wells in your area, looking for depth of the wells and depth to water. Usually, the darker blue patterns represent increased chances of encountering groundwater.

KGS has also published a new set of water well and spring maps at a scale of 1:100,000 for Kentucky that give a quick assessment of wells and springs in an area. You can see these maps online at: by typing in “water well and spring” in the keyword search window.

We also recommend running an online water well search to see whether there are other water wells in your area. See “How deep is the groundwater on my land?” below for details.

When should I think about drilling a new water well?

Water wells are like most things--they don't last forever.  Listed below are several guidelines to help you determine if you should consider having a new well drilled.

(1)  Over time, generally years, some wells become less useful by allowing surface water into them, especially during or after rainfall.  Typically this is evident when the well water becomes cloudy or muddy.  The surface water may bring bacteria or other contaminants into the well.  If you notice your well water becoming cloudy or muddy more frequently, you should disinfect your well after each episode.  See " What should I do if my well contains Total Coliform or E. coli bacteria?" for instructions on how to disinfect your water well.  The increased occurrence of cloudy or muddy water is an indication that you may need to install a new well.  If you own a newly constructed well (less than 5 years old) and your drinking water becomes cloudy or muddy after a rain, then your well may be improperly constructed.  You should contact your driller to discuss possible ways to fix the problem. 

(2) If the bacteria levels do not decrease to zero after you have repeatedly disinfected your well over several weeks, contaminated surface water or shallow groundwater may be entering the well.  The well casing may have been cracked or the surrounding area may have been contaminated by a leaky septic tank.  To alleviate the problem , you may need to install a deeper well away from the contaminated area. 

(3) Shallow wells (generally less than 40 feet deep) are much more susceptible to contamination than deeper wells.  If you own a well less than 40 feet deep, you may improve the overall quality of your drinking water by installing a deeper well.

(4) Regular maintenance of your water well is very important.  This would include disinfecting, cleaning the well house, checking the well casing for cracks, checking to see if the well cap or cover is on properly, and inspecting the pump and pressure tank.  If the well casing becomes cracked, the well is susceptible to contamination.  The cracked casing should be replaced, if possible, or a new well installed.

Generally, installing a new well means drilling at least 50 feet from the existing well and possibly increasing the well depth and casing.  All installation of and modifications to water wells should be done by a Kentucky Certified Water Well Driller.  See < > for a list of certified drillers.

How do I locate a water well driller?

You can select a water well driller and talk to them about their success rate in your area by checking the Kentucky Division of Water's list of certified well drillers online at < >, or you can call the Division of Water in Frankfort and request a free copy at 502-564-3410.

How deep is the groundwater in my area?

A good way to determine depth to groundwater in your area is to check the depth to water for other water wells in the area. You will need to determine your site’s latitude and longitude. You can do that online by using Google Earth. Enter the closest town or even a cemetery or school name in the place name box, enter Kentucky as the state, then press the “search” button. Once you get the correct topographic map, change the coordinate system on the left side of the map from UTM (default) to D/M/S (degree/minute/second). Pan around the map until you find your site, then left-click on that location and write down the coordinates listed above the map. Proceed to the KGS web site <> and perform the water-well search (use the tutorial provided if you don’t know how to run a search). You can also search directly by interactive map using the “KYGeoportal” - this takes a little longer if you don't have a fast computer. The quickest type of search is the radius search - plug in the lat/lon you wrote down, and select a radius (1 mile should do). This will give you a list of water wells in the area - check the depth to water on each of the wells, which provides an idea of how deep you'll need to drill.

Be aware that water wells located on hills or ridges may have a greater depth to groundwater than wells in valley bottoms (which are often closer to the underground water table), and will be more expensive to drill due to greater depth.

What is the quality of groundwater in my area?

After running a well search in your area, check the results page to see if any water quality analyses are available for the wells that came up in your search. The box on the results table labeled “Quality Analyses?” will be yellow and contain a check-mark if analyses are available. If none are available, you may have to have your water tested by a laboratory to determine its quality.

Does KGS offer water-quality analysis for the general public?

Although KGS does have a water-quality laboratory, it is reserved primarily for research projects and is not available to the general public. You can check the internet or yellow pages for “Water Treatment Services” or contact your local health department, cooperative extension service or water company for more information on having your water tested.

What’s the difference between groundwater and surface water?

Water is generally classified into two groups: surface water and groundwater. Surface water is just what the name implies; it is water found in a river, lake or other surface impoundment. This water is usually not very high in mineral content, and is often called "soft water" even though it is probably not. Surface water is exposed to many different contaminants, such as animal wastes, pesticides, insecticides, industrial wastes, algae and many other organic materials.
Groundwater is water that is contained in a subsurface layer of soil or rock. There are many sources that recharge the supply of groundwater, including rain that soaks into the ground, rivers that disappear underground and melting snow. Because of the many sources of recharge, groundwater may contain any or all of the contaminants found in surface water as well as the dissolved minerals it picks up underground. However, groundwater commonly contains less contamination than surface water because the rock tends to act as a filter to remove some contaminants. Groundwater that contains dissolved minerals such as calcium and magnesium above certain levels is considered "hard water." In Kentucky, where rocks and minerals such as limestone, gypsum, fluorspar, magnesium, and pyrite are common, well water is usually very high in calcium content, and therefore considered "hard".  

What is hard water?

Hard water is the most common problem found in the average home. Hard water is water that contains dissolved hardness minerals (calcium and magnesium) in amounts greater than 1 grain per gallon (a typical aspirin contains about 5 grains of material for comparison, and if dissolved in a gallon of water, would add 5 grains of aspirin to it). The dissolved minerals present in hard water can accumulate in the form of a hard scale which can build up and eventually clog pipes and damage water-using appliances. These minerals also affect the ability of soap to clean kitchen and bath surfaces, dishware and laundry, and even human hair and skin.

The water from my faucet smells bad. What causes that?

Strong, “rotten-egg” odors in water are usually the result of the decomposition of underground organic deposits. As water is drawn to the surface, hydrogen sulfide gas can be released to the atmosphere. In strong concentrations, this gas is flammable and poisonous. It rapidly tarnishes silver, and is toxic to aquarium fish in sufficient quantities. As little as 5 parts per million (0.5 ppm) hydrogen sulfide can be tasted in your drinking water.

There is a sinkhole on a property I am considering buying. What should I do about it?

About 55% of Kentucky’s land surface is underlain by limestone and 38% is affected by obvious “karst geology”. Karst is the geologic term for areas with sinkholes, caves, underground streams, and springs. Sinkholes can indeed be a problem if you are considering buying or building a house on or near a sinkhole. Young sinkholes, usually caused by cover-collapse, are occasionally found to be at the location of an older sinkhole that was previously filled in. Cover-collapse sinkholes can sometimes be repaired but must allow water to infiltrate. Sinkholes are also prone to flooding.

If you suspect that there is a sinkhole or spring in the area where you want to build, consult a professional geologist or hydrogeologist to investigate the site first. Check the local yellow pages under “geologists.” Building on sinkholes is not a good idea, but if it can’t be avoided have a geotechnical investigation done and the foundation designed by a professional engineer. Please see the KGS web pages on karst geohazards at <> for more information.

Water has started “ponding” in my yard after a heavy rain. What is happening, and should I be concerned?

A number of factors may be responsible for ponding water. Poor drainage is usually the culprit. However, you could have a sinkhole that is stopped up, or surface runoff coming from an adjacent property, or a leaking septic system may have saturated the soil thereby causing a drainage problem. If ponding occurs regularly, you should be concerned and seek help to get the problem identified and remedied. Sometimes a “French” drain (trenches filled with gravel and covered with soil or sod) may help divert water, or the lot may need to be re-graded to allow proper drainage. Also refer to the sinkhole question above.

What should I do if my well contains Total Coliform or E. coli bacteria?

If your well contains Total Coliform and/or E. coli bacteria, you are advised not to use your well water for drinking or cooking until the well has undergone a shock chlorination treatment. The well should be properly treated with chlorine (bleach), resampled, and determined to be free of Total Coliform and/or E. coli before using for drinking and cooking. For information on how to chlorinate your well or sampling your well contact your County Health Department. Information pertaining to chlorinating water wells can be obtained by visiting the following websites:

What areas in Kentucky are vulnerable to groundwater contamination ?

It is possible for groundwater in any part of the state to become contaminated. Rainwater that soaks into the ground reaches most aquifers (water-bearing geologic formations) in Kentucky in a few hours to a few years. Therefore any source of pollution can conceivably travel through an aquifer into a water well supply, depending on the type of aquifer and the type of pollution. In Kentucky, however, many water-quality problems with groundwater are caused by poor well construction or deteriorated well conditions. The best defense against pollution is to use a certified water well driller to construct the well in accordance with state regulations and to routinely service and maintain the well and associated plumbing. Owners of domestic wells should also be aware of potential pollution sources, such as their own septic tank, service stations, waste-handling operations, factories, animal feedlots, and other industrial sites, near their home. Water samples from all water-supply wells should be tested annually.

The aquifers most vulnerable to ground-water contamination are those in which ground water travels relatively quickly. Those include the limestone, or karst aquifers, in the Inner Bluegrass, the Eastern Pennyroyal, and the Western Pennyroyal. Sand and gravel aquifers along the Ohio River and some of the other larger rivers are also vulnerable to pollution. The shallowest sand and gravel aquifers in the Jackson Purchase are also somewhat vulnerable. The bedrock aquifers of the eastern and western coal fields are comparatively less vulnerable to contaminant pollution, but can be significantly affected by coal mining.

My well water is iron rich. Can I drink it?

Iron present in well water is most likely coming from the surrounding rock or sediments which are iron rich.  The iron dissolves in the well water and becomes noticeable as light to dark brown stains on your sink, toilet, and clothes.  Iron-rich groundwater (well water) is a nuisance more than a health concern.  Iron concentrations found in groundwater are generally not harmful to humans. The U.S. Environmental Protection Agency has assigned a secondary drinking water standard for iron of 0.3 mg/L, which is based on offensive taste, odor, color, corrosion, etc. Secondary standards apply to public water supplies.  Private water supplies (water wells) are not subject to the secondary standard, but well owners should use the standards to evaluate the quality of their drinking water. 

What about water wells that are abandoned or not in use?

Abandoned water wells (wells not in use) need to be properly plugged by a certified water well driller.  Water wells that are not maintained or used may act as conduits for surface water and contaminants to enter the groundwater system. Plugging unused water wells alleviates the possibility of chemicals and other contaminants from entering the groundwater system. Also, large diameter wells (2 feet and larger) which are not used and not maintained may be hazards to small children and animals. Properly abandoning these large diameter wells will ensure that you are and your family are safe. Please note that improperly abandoned wells are the responsibility of the land owner.