Different Bacteria in Water Systems

When it comes to water treatment and ensuring the safety of your water supply, understanding the various bacteria that can inhabit water systems is crucial. All bacteria are different; they enter the system differently, evolve differently, spread differently, and cause different types of illnesses.

In this blog, we’ll explore different types of bacteria that can be found in water systems and the importance of water treatment in ensuring safe and clean drinking water.


Pseudomonas bacteria are common in many natural environments, such as, in soil, water, and on plants. While many species of Pseudomonas are harmless, some can be opportunistic pathogens. In water systems, Pseudomonas can form biofilms, slimy layers that adhere to surfaces like pipes and faucets and allow for other more harmful bacteria to form. These biofilms may reduce water flow and quality, and in some cases, lead to infections in vulnerable individuals.

These bacteria are often found in carbon filters, cooling towers, drinking water dispensers, and water taps. Effective water treatment methods are crucial to control and manage Pseudomonas in such systems.

E. Coli (Escherichia Coli)

Escherichia coli, or E. Coli, is a familiar name when it comes to water quality and safety. While many strains of E. coli are harmless, some have the potential to cause severe health problems. This type of bacteria is typically associated with raw food; however, it can infiltrate the water system when animal faeces contaminate the ground and surface water. If not adequately treated before entering the public water supply, this can become a concern.

What sets E. coli apart from other bacteria is that even a small intake of contaminated water can make you ill, making it particularly dangerous.


Coliform bacteria are a group of bacteria that are commonly used as indicators of water quality. They are naturally present in the environment and are found in the faeces of all warm-blooded animals and humans.

Although coliform bacteria themselves are generally not harmful, their presence in drinking water serves as a critical indicator that disease-causing pathogens may also be present in the water system.

Testing for all potential waterborne pathogens is a complex, time-consuming, and costly process. In contrast, testing for coliform bacteria is a relatively straightforward and inexpensive. Identifying coliform bacteria in a water sample signals the need to investigate and rectify the source of contamination, ensuring the restoration of safe and clean drinking water.


Legionella bacteria is a highly dangerous bacteria that can cause severe respiratory illness known as Legionnaires’ disease. They thrive in warm water environments at temperatures between 20C and 50C, such as cooling towers, hot water tanks, and plumbing systems.

When water droplets containing Legionella are aerosolised, the inhalation can lead to infections and respiratory illnesses, particularly in individuals with weakened immune systems or preexisting health conditions. To prevent Legionella outbreaks, it’s crucial to carry out regular Legionella Risk Assessments on an annual basis.


Understanding how these bacteria manifest in water systems and having effective control measures in place is paramount to ensuring safe and clean water for consumption. Regular monitoring and stringent water treatment protocols are essential for ensuring that the water you use every day is free from these harmful bacteria.

Our experts know what to test for and how, get in touch today on 018 252 775 or info@Aquachem.ie to talk to someone about setting up regular water sampling in your premises.