Most people assume that public water is always bacteria-free. After all, public water systems are designed to deliver water that is safe to drink and to use for daily tasks like bathing and brushing your teeth. However, bacteria and other contaminants can sometimes contaminate households with public water. When this happens, residents with public water will likely receive a boil water advisory to alert them that the water is not safe to consume.

Homeowners with well water often do not consider the need to keep their water bacteria-free. However, without proper water treatment and maintenance, bacteria often enters homes with well water. In our area, approximately 1 in 6 wells are found to contain bacteria when tested. Your water supply could also become contaminated after a flood or another disaster.

Fortunately, it’s relatively simple to ensure your water is safe to drink. Here’s a look at some of the common microorganisms that can be found in your drinking water and how to detect them.

Microorganisms That Can Be Found in Drinking Water

We, of course, want our water to run clear from the taps in our homes, but there can be more than meets the eye in your drinking water. What are some of the main microorganisms potentially found in drinking water?


Two main groups of bacteria found in tap water are:


1. Coliform Bacteria

Coliform bacteria is a group of bacteria that is naturally found in soil, plants and the digestive tracts of people and animals. Not all bacteria in this group are considered harmful if present in the water supply, but a subgroup, fecal coliforms, can cause illness. For example, drinking water with the bacteria Escherichia coli (E. coli), a fecal coliform, can result in intestinal inflammation. An E. coli infection can cause symptoms such as cramping, diarrhea, vomiting and fever. This infection typically requires treatment with antibiotics.




Testing is the only way to confirm what kind of bacteria is present and in what levels in the water supply. If your water tests positive for coliform bacteria, this may indicate a problem with your water system and there is potential for E. coli to grow. If you have a system to treat bacteria, part of the system may need to be repaired or maintained. If you do not have a treatment system, you should consider treating your water to ensure all potentially harmful bacteria are destroyed.

2. Heterotrophic Bacteria


Heterotrophic bacteria are generally found in all water supplies. These bacteria use organic substances in their environment, such as sugar, to survive and reproduce. Drinking water is tested for this type of bacteria using the heterotrophic plate count. While a higher count of heterotrophic bacteria may indicate an environment is ripe for the development of other kinds of bacteria, heterotrophic bacteria are typically not considered dangerous.


If water testing does indicate high levels of heterotrophic bacteria, further testing for other bacteria, such as E. coli, is likely needed as well. If you are concerned about heterotrophic bacteria alone, standard approaches to water treatment can reduce or eliminate this type of bacteria.



Viral pathogens can be transmitted through drinking water. Some of the potential viruses found in drinking water include:


1. Adenovirus


Adenovirus infection can cause illnesses such as the common cold or flu, resulting in symptoms like fever, cough and a sore throat. Adenoviruses can also cause more serious respiratory infections, such as bronchitis and pneumonia. Illnesses like pink eye and gastroenteritis, which results in nausea, vomiting and diarrhea, can also be caused by adenoviruses. This type of illness more commonly results in mild symptoms, but serious infection is possible.


Illness caused by adenovirus is most commonly transmitted through the air or contact with someone who is sick, but it can also be a waterborne illness. Adenoviruses have been detected in drinking water, wastewater, swimming pools and natural bodies of water. Treating drinking water with chlorine helps to reduce waterborne viruses, such as adenovirus.

2. Hepatitis


Hepatitis A and hepatitis E can be transmitted via contaminated drinking water or food. Both forms of this disease affect the liver. Hepatitis A, which can be prevented via vaccination, can last up to two months. This disease causes symptoms including jaundice (a yellowing of the skin), stomach pain and fatigue. Hepatitis E is present in the stool of infected people. It can cause similar symptoms to hepatitis A, but many people have no symptoms at all.


Hepatitis A can be potentially spread through drinking water in private wells. If the water in a well becomes contaminated with feces, it is possible that drinking that water could result in infection. This type of contamination can happen as a result of sewage overflow or poorly maintained well systems. Hepatitis E is found across the entire world, but it’s more commonly found in areas with poor sanitation and fewer resources. Like hepatitis A, hepatitis E can be transmitted via fecal contamination in drinking water. Testing procedures can help to determine if the hepatitis virus is present in your water supply.

3. Norovirus


Noroviruses cause what is commonly referred to as the stomach flu, which is different from the flu caused by an influenza virus. Norovirus infection causes symptoms such as nausea, vomiting, diarrhea, stomach pain, fever and headache. Illness caused by a norovirus can also lead to dehydration. A virus in this group, which contains many different strains, can be transmitted via direct contact with an infected person, contact with an infected surface and via contaminated food or drink. Illness caused by a norovirus typically resolves within a few days.


Noroviruses are found all over the world. Drinking water can become contaminated with virus particles when it comes into contact with feces. In the case of a private well, stormwater or sewage runoff can contaminate the water supply, introducing pathogens like norovirus. Shallowly dug wells are typically more susceptible to this kind of contamination. Testing can determine whether or not your water supply is contaminated with norovirus.

4. Rotavirus


rotavirus vaccine became available in 2006. Prior to that, the virus infected nearly all infants and young children. Rotavirus causes severe diarrhea, vomiting, fever and stomach pain. While more common in young children, it can infect older children and adults. Like other viruses that affect the digestive system and cause vomiting and diarrhea, rotavirus can lead to dehydration. Symptoms can last anywhere from a few days to more than a week. Rotavirus infection occurs when virus particles enter the mouth. This can happen due to touching a contaminated object and then the mouth or when drinking or eating contaminated food.


Rotavirus is present across the entire world. Simple steps like handwashing can go a long way toward prevention. Well water can become infected with rotavirus when sewage and stormwater overflow occur. If you are concerned about rotavirus in your drinking water, testing procedures can be done to detect virus particles. If virus particles are present, whether rotavirus or a different virus, keep in mind that filtration is likely not a sufficient strategy. Virus particles are very small and will likely remain in the water despite filtration.



Protozoans are neither bacteria nor viruses, but some of these single-celled organisms can cause illness when ingested. Parasitic protozoans that can be found in drinking water include:


1. Cryptosporidium


Cryptosporidium, often referred to as Crypto, is an enteric protozoan, which means they infect the GI tract. There are different species of Crypto, some of which can infect people. Like many other waterborne illnesses, Crypto can be contracted when someone ingests fecal matter infected with the microorganism. The main symptom of Crypto infection, referred to as cryptosporidiosis, is watery diarrhea. People can also experience cramping, fever, vomiting, dehydration and weight loss. Symptoms usually last for a couple of weeks, but the illness can persist for a month.


Crypto can survive for long periods of time in the water, and it is typically resistant to chlorine treatments. Well water can become contaminated with Crypto when it comes in contact with wastewater that contains feces from an infected person or animal. Boiling or certain types of filtration can kill the protozoan and make the water safe to drink.

2. Giardia


Giardia is another common cause of enteric infection. It can be found in the United States and around the world. Symptoms of giardiasis are similar to Crypto. It can cause diarrhea, cramping, vomiting and dehydration. Symptoms last for a couple of weeks, though they can persist for longer. Ingesting contaminated feces is a common mode of transmission, whether through water, food or touching a surface.


Like Crypto, Giardia is often resistant to chlorine treatment of drinking water. If your well water has been contaminated by sewage or stormwater runoff, Giardia contamination is possible. Boiling and filtration, such as reverse osmosis, can render Giardia inactive in drinking water.


Treating Your Water for Microorganisms

Microorganisms in the water supply can be cause for concern. If you have your water tested and the results show bacteria, or viral or protozoa contamination, there a few different options for making the water potable.




Boiling is one of the most reliable ways to render water potable. The Centers for Disease Control and Prevention recommends bringing water to a rolling boil for one minute. For people who live in higher elevation areas, more than 6,562 feet, water should be boiled for three minutes. Boiling water can effectively kill microorganisms, including bacteria, viruses and protozoans. Microorganisms are sensitive to heat, and bacteria are typically inactivated the fastest when boiled. Afterward, water can be stored securely, cooled and safely used for drinking. While reliable, boiling your drinking water is mostly recommended in emergency situations, such as a natural disaster.

You can also consider the installation of a water distillation system, which boils water to remove contaminants. This type of system boils the water and collects it when it is in vapor form. This process can remove many contaminants, including protozoa, viruses, bacteria and a number of different chemicals.





While boiling inactivates microorganisms, rendering them unable to infect when ingested, filtration physically removes contaminants from drinking water. Filtration is designed to remove microorganisms, as well as other contaminants such as chemicals and heavy metals. While filters can be very effective, they cannot remove contaminants completely. When considering a filtration system, it is important to understand different filters have different levels of efficacy.


When considering a filtration system for your home, consider the size of the filter. For example, microfiltration systems have a pore size of 0.1 microns, while ultrafiltration has a pore size of 0.01 microns. Both microfiltration and ultrafiltration systems tend to be effective at removing microorganisms, but they are not very effective at filtering out chemicals. Reverse osmosis, another filtration option, has an even smaller pore size and can remove bacteria, viruses and protozoans, as well as many chemicals.

A water filtration system can be as simple as a pitcher with a filter. However, it is also possible to install filters on your home’s water taps, or you can opt for professional installation of a filtration system under the sink.



Water disinfection can be accomplished using chemicals like chlorine, chlorine dioxide, chloramine and ozone. Utilities often use chlorination to deliver safe water to their customers. Private wells can also undergo chemical disinfection. While this process can be effective at removing many contaminants, protozoans like Crypto and Giardia are resistant to chlorine. Safety precautions are essential whenever working with chemicals in your home. Water can also be disinfected through physical methods, such as radiation.

Ultraviolet Systems

Ultraviolet (UV) light is another way to disinfect drinking water physically. UV systems have demonstrated efficacy against protozoans like Crypto and Giardia, as well as various bacteria and viruses. These systems typically involve prefiltering the water. Any suspended particles in the water can make UV disinfection less effective. After filtration, UV lamps are used to treat the water. The UV light disrupts the cellular function of microorganisms, rendering them unable to grow in your water system.

UV disinfection systems do not alter the taste of your drinking water, and they work without the use of any chemicals, like chlorine. The systems are also relatively compact, low-maintenance, energy-efficient and environmentally safe.

Get Access to Healthy and Safe Water With Long’s EcoWater



Your family should have access to water in your home that is safe and free of contamination. At Long’s EcoWater, we offer comprehensive water testing services in the eastern Pennsylvania area, so you can know exactly what is your water. If you discover that bacteria or any other contaminant is present in your drinking water, our ultraviolet light system and/or drinking water system can safely and effectively treat your water. You want to keep your family healthy and safe each time they take a drink of water, and we can help. Reach out to us to learn how our water professionals can help give you peace of mind and ensure your home’s water is clean and safe.