10 Methods to Test Well Water for Bacteria and Pesticides

Relying on your well water can save you from several problems. You don’t have to deal with the pollutants or chemicals present in municipal water. However, it is not to say that well water does not come with its own set of problems. According to the US Geological Survey (USGS), around one-fourth of 2000 private tested wells had at least one contaminant which could be harmful to health.

Well water is vulnerable to harmful substances. Rainwater can absorb minerals as it flows through the ground and can mix with the aquifers. However, not all compounds are dangerous. Some are beneficial to health, while others give a bad taste and nasty smell to the water. Therefore, it is better to be cautious and know your water composition before you consume it.

Microorganisms are one of the most common substances that can be found in water. On the other hand, pesticide contamination can happen in unusual cases. In this article, we will tell you how to test your water for these contaminants and how to deal with them properly.

Bacterial Testing Methods

Laboratory Testing

The taste, smell, or odor of water can give a hint of contaminants in the water. However, it is not a definite way to determine the type of contaminants polluting the water. Some compounds do not alter the smell, taste, or color of water and, hence, go undetected. These compounds can still be harmful to health. The Center for Disease Control and Prevention (CDC) has established a Water Quality Indicator (WQI) test to measure the presence and concentration level of harmful germs in the water. 

pH of Water

water pH level

The pH level shows the acidic and basic level of water. In addition to changing the taste and color of water, extreme differences from the normal pH level indicate the presence of heavy metals. These metals can leach off the iron and lead pipes. The scrap particles can enter drinking water. The ingestion of these harmful substances can increase the risk of health problems. 

Total Coliform Bacteria

These microorganisms can be found in the soil, plants, surface water, and digestive systems of warm-blooded animals. Coliform bacteria do not cause any diseases, but their presence alone indicates that other harmful microorganisms may also be present in the water. A high concentration of coliform bacteria increases the likelihood of other disease-causing germs in the water. Moreover, microorganisms can be hard to test in water; therefore, the coliform bacteria test is useful for their detection. 

Fecal Coliforms / Escherichia coli (E. coli)

Fecal Coliforms

Fecal coliform bacteria are also a type of coliform bacteria. These microbes are mostly found in the excreta and digestive systems of humans and warm-blooded animals. E coli. (Not the deadly E coli. O157:H7) also belongs to this class of bacteria and can be detected through WQI tests. Although not harmful, their presence in water is a clear signal that feces have made their way into the well water. The potential harmful microbes present in this unhygienic water can result in diarrhea, stomach pains, dysentery, typhoid, and hepatitis.

The Environmental Protection Agency (EPA), lists some additional tests to check the presence of bacterial or pesticide contamination in water:


The CDC recommends a nitrate test for all private wells. Nitrate is found naturally in foods but can also form as a result of industrial, agriculture, fertilizer, and sewage discharge. It can make its way to wells as the water flows through the surface and seeps into groundwater. High concentrations of nitrates in the water can cause adverse effects on health. Particularly, pregnant females and infants can be exposed to harmful nitrate effects. Nitrate tests are best performed after summer and spring rains.

Sulfate Bacteria

Many times the water can have a rotten egg-like odor. This can be due to the presence of hydrogen sulfide, sulfate bacteria, or sewage waste seeping in the water. The sulfate bacteria can convert the sulfates present in the water and form hydrogen sulfide gas. The strong odor of the water is clear evidence of the gas. Usually, hydrogen sulfide gas and sulfates are not harmful, but the high content ratio can cause dehydration and nausea. 

Water Sample Collection

To get your water tested, you need to provide a sample of your water to the testing laboratories. Laboratories may provide specialized containers to collect the sample. In this case, make sure to follow the provided guidelines. Water samples containing some bacteria need to be stored in sterilized containers and kept under specific conditions. The more you follow the instructions, the higher will be the credibility of results. In some cases, the laboratories may send trained personnel to collect the sample. You can ask the laboratories for their specific procedures or if they provide the service. 

Pesticide Testing

Pesticides are chemicals used to kill weeds and pests that can damage crops. These chemicals do not usually enter the water unless there is an agricultural area near your well, generally in one-mile proximity.

Pesticide and herbicide laboratory testing is a costly method. Routine testing should only be done if you suspect agriculture or fertilizer waste mixing into the water. If many people in the locality are facing the same water problem, it can be a red signal that dangerous chemicals have dissolved in the water. If you witness pesticide activity nearby or waste being disposed of, get your well water checked as soon as possible. Pesticides are uncommon but can be life-threatening. You should get the water tested for nitrite/ nitrate concentrations in the water. The local health department can guide you on the nitrates or other pesticides that may have entered the water in your area. 

Water Testing Kits

Test drinking water

You can also check for bacteria and pesticides using water testing kits. This is a simple and economical method to test the water. There are various kits available in the market which can test for bacteria, pesticides, lead, and other substances. Do not blindly buy any water test kit. Inform yourself better and purchase a quality test kit. Test kits indicate what they are testing for along with a user guide. A significant drawback to using a test kit is that it is less reliable and lacks the laboratory testing method’s accuracy. 

Preventive Measures

  • The well should be protected from the outside environment. A change in the odor, color, or taste of water is an indication that substances have mixed with the water.
  • Wells should be built appropriately. Corrosion of the well casing can cause holes in it. The opening provides a passage for foreign bodies to enter the water.
  • Check periodically for damaged cap or cracks in the well casing. It is preferable for the housing to be a good level above the ground.
  • A sloping area around the well can effectively keep surface wastes from seeping into the well.
  • Get your well tested periodically. Particularly after well repairs or in the case of natural disasters, such as floods and rainfalls.
  • Do not dispose of any waste material in abandoned, dry, or normal wells.
  • For building, modifying, or closing of a well, contact a licensed well driller.

 How to Deal with the Bacteria and Pesticides in Well Water

The national testing laboratories can help you identify the source of contamination in your water and provide various packages accordingly.

Water Research Center suggests several testing methods and guides according to the type of contaminants in your water and the area you are living in. Based on the analysis report of your well water, they can recommend the most suitable method to obtain germ-free water. The solution can include chlorination systems, water softener, distillation, reverse osmosis, ultraviolet, or UV system.

Until you get your water treated, try to use boiled or bottled water. However, if there are nitrates in your water, boiling will only increase the contaminant count. Bottled water may be your safer option. After disinfecting the well, recheck the well water for any residual contaminants. If the problem persists, building a new well or water filtration methods can be the preferred choices. 


It is vital to get the well water tested once every year for contaminants, particularly the ones mentioned earlier. However, these tests can be costly, so try to narrow down the possible contamination causes as much as possible. Look for any change in the odor, taste, or color of the water. The local health department can also inform you about any contaminants present in the vicinity. You must get the water checked in case of unusual circumstances such as natural disasters or nearby placed agriculture and industrial discharge. State environment departments can check for nitrate, total coliform, pH, fecal coliform, and organic compounds. If you want to get other tests performed, the local health department provides a list of licensed laboratories near your locality. You can also visit their website to obtain information about the groundwater in your area or contact EPA Safe Drinking Water Hotline at (800) 426-4791.

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