Water is a great resource but one that we can easily take for granted. We turn on our taps and expect to get healthy, whole water and in most cases we do. However, water, even after it has been treated by the water companies can still contain a small number of bacteria. This bacteria, given the correct circumstances can breed, multiply and cause problems within our water systems. Water systems such as bore holes and private spring supplies can also be contaminated with animal and human faeces during rainfall and snow melts. Damp conditions in tanks can lead to black mould growing on tank walls. Thankfully bacteria and mould are some of the 5 Things that Huwa-San kills.

There are several bacteria that can live in our water systems that are hazardous to our health. They live in the body of the water (planktonic) and also in the biofilm (sessile). Generally, bacteria in the body of the water are relatively easy to kill but killing bacteria in a biofilm is more difficult to achieve.


A biofilm is a complex matrix of bacteria which grows on the inside of water pipes. It can contain bacteria such as Legionella, Pseudomonas, E. coli, and Staphylococcus. These bacteria, as they are captured in a sticky matrix, can be extremely difficult to kill and remove.

A biofilm is formed in a number of stages which include:
  1. Attachment: a biofilm starts to form on the inside of a pipe’s surface, when free floating bacteria can attach themselves to the pipe by weak, reversible adhesion.
  2. Adhesion: if the bacteria aren’t immediately removed, they have time to anchor themselves more permanently by secreting polysaccharides. The polysaccharides are a sticky substance which covers the bacteria making them much harder to remove.
  3. Aggregation: Bacteria then grow quickly in columns from this base layer.
  4. Growth: the columns allow free access for the water salts, suspended material and iron. This allows oxygen and water through the biofilm and further growth occurs.
  5. Detachment: Biofilm grows to a certain level and then larger parts detach and float away to colonise other parts of the system.

Legionella Bacteria

One of the main bacteria that we associate with water systems is Legionella bacteria which can cause Legionnaires’ disease or other lesser illnesses. Like humans, Legionella bacteria likes to be kept warm, sheltered and provided with a food source. Therefore, given a food source of  rust,  warm temperatures between 20-45°C and a biofilm for shelter it will multiply. Legionella bacteria can multiply extremely quickly given the correct conditions. A single bacterium can become hundreds of thousands within a few days. High levels of Legionella bacteria have led to outbreaks of Legionnaires’ disease throughout the UK. There are several noticeable outbreaks during the past ten years. These include the cooling tower outbreak in Edinburgh 2012, a domestic water system outbreak in a Ludlow Hotel 2017 and a spa pool outbreak in Bournemouth 2019.

Legionella Bacteria : The route to infection from Legionnaires’ Disease

For a person to be infected with legionella bacteria from a water system there are a number of things that need to happen at the same time.
1) Contamination: Water systems have to be infected with legionella bacteria
2) Amplification: Conditions have to allow the bacteria to multiply
3) Transmission: Bacteria must be in the form of an aerosol. This could be from a shower, cooling tower or a fountain for example.
4) Exposure: Victims have to come in contact with the contaminated water.
5) Susceptibility: The victim has to be susceptible to the bacteria. People over 50, who smoke, who are male and are immunosuppressed as considered to be within a higher risk group.

Legionnaires’ disease in the worst case can be fatal. When an aerosol from a contaminated water system is inhaled by the victim the bacteria is transmitted to their lungs and causes disease. However, it can also cause long term illness and suffering for the victims who survive.

Pseudomonas Aeruginosa

Pseudomonas Aeruginosa belongs to the “Pseudomonads family” and is also a known biofilm producer. Pseudomonas will cause problems in a hospital environment as it is an “opportunistic” organism. It causes infection where normal immune defences are weakened. The very young and the very old are particularly vulnerable.
There was an outbreak in a Belfast Hospital in 2012 which killed 3 babies who died from sink taps being infected.

Pseudomonas can be transmitted through the water but also has the added problem that it can be transmitted person to person.

It can cause a number of infections which include:

  • urinary tract infections (UTI)
  • central nervous system infections
  • ear infections, bone and joint infections
  • gastrointestinal infections and skin and soft tissue infections

At its very worse Pseudomonas can be fatal.


E Coli is generally found in water from private supplies and bore holes rather than in water provided from the water companies. However, it has been found in occasionally in tank fed systems.
E Coli is a bacteria that is common to human and animal intestines and forms part of the normal bacteria that exist in the bowel. It can enter water systems such as rivers and streams from human and animal faeces. Occasionally tank fed water systems can be infected through bird droppings.
Most E Coli does not cause disease but the virulent strains such as E Coli 0157 can cause gastroenteritis, urinary tract infection, neonatal meningitis and Crohn’s disease. E coli can be caused by eating infected food or swallowing infected water.
Outbreaks of E Coli have been associated with private supplies such as springs. In 2018 one in ten private drinking water supplies in Scotland were found to contain E Coli

Staphylococcus Aureus

Staphylococcus Aureus is a bacteria that causes significant problems in a hospital setting. It can colonise human skin and mucous membranes without causing any issue. However, it is another opportunistic bacteria. If  Staphylococcus enters the body through broken skin it can result in anything from a mild to life threatening illness. Staphylococcus can cause skin and wound infections, eczema, abscesses, joint infections, infections of the heart valves and pneumonia.
Some strains of Staphylococcus are easily treated with antibiotics however some are resistant such as Methicillin-resistant staphylococcus aureus (MRSA) which is a worldwide problem in clinical medicine.

Aspergillus Niger AKA Black Mould

There are over 200 Aspergillus species and the majority do not cause any ill effects to humans. However, Aspergillus Niger is one of the top three Aspergillus species that cause ill health. Black Mould is a type of fungi that is black in colour and requires very low levels of nutrient to grow and multiply. It can be found in a number of places including
• Cold water storage tanks
• Soil, compost and rotting leaves
• Damp buildings
• Air conditioning systems
It is unlikely to cause ill health in people with good immune systems but can cause serious problems for hospitalised patients.  This is a particular problem in those with a lung condition or a weakened immune system.


These are just some of the bacteria and fungi that can cause ill health in humans and animals through water, surface or air contamination. Huwa-San disinfectant have been tested in the laboratory and the field against a whole host of micro-organisms including those above. It has been found to be effective against Legionella, Pseudomonas, E Coli, Staphylococcus and Aspergillus Niger as well as other bacteria, moulds, and viruses.

Please click the link to find out more about Huwa-San TR50

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