Despite vast improvements in water safety, drinking water is still occasionally contaminated with pathogens and waterborne illnesses continue to occur.
Advances in microbiology are providing new ways for us to study and understand what microbes live and thrive naturally in our water distribution systems and how we can maintain clean, safe water in buildings and especially in the last few metres – at point of delivery.
In this blog post, we explore the bacteria, viruses and common contaminants found in water and the disinfection methods used to keep them at bay.
Perfectly safe water contains millions of non-pathogenic microbes in every glassful — and this is just as true of bottled water as it is of tap water. The entire water distribution system (every reservoir, well, tank and pipe etc), are home to multiple species of bacteria, algae, invertebrates and viruses, most of which are completely harmless to humans. However, some are still dangerous such as E. coli, Giardia, and Cryptosporidium, which can cause gastrointestinal problems and flu-like symptoms commonly attributed to undercooked or improperly stored food.
Water companies have a duty of care to protect our water to the point of supply. However, commercial building managers are responsible for water safety and hygiene within water distribution systems and for water system disinfection from the point of source (mains-fed supply, private supply through borehole etc), to point of supply (tap, shower etc).
Microbiological and organic contaminants cannot always be detected through sight, smell or taste. Good water hygiene and water disinfection techniques, including methods of disinfection and purification of water, are essential to protect human health and guard against common bacteria, viruses and contaminants.
Single-celled organisms lacking well-defined nuclear membranes and other specialised functional cell parts, often reproduce by cell division or spores. The bacteria may be free-living organisms or parasites. Bacteria (and fungi) are decomposers that break down the wastes and bodies of dead organisms and microbes naturally found in water, making their components available for re-use. Some bacteria are helpful to humans, while others are harmful.
Parasitic infectious microbes, composed almost entirely of protein and nucleic acids, can cause disease(s) in humans. Pathogenic viruses are responsible for gastroenteritis, hepatitis and many other strains are the main targets for detection, filtration and removal via disinfection, sanitisation and purification of water.
Other common contaminants that can be found in water include, but are not limited to:
Whilst temperature control is the main form of defence against bacteria, viruses and other contaminants, it is not always sufficient in some complex water systems. The following water treatment methods can therefore be applied to ensure the water is clean and safe for use.
Chlorination is the process in which chlorine or a form of chlorine is added to water for disinfection and control of microbiological contaminants found in water.
Chlorination is also used in the oxidation of dissolved iron, manganese and hydrogen sulphide impurities, making water appearance clearer. Chlorine is added to water by public water companies making it safe to drink. Today, forms of chlorine, such as Ultralox40®, are widely used as methods of disinfection and secondary disinfection of water distribution systems within buildings.
Ultralox40® is a form of chlorine approved for potable water. It is ideal for use in water hygiene and pipework treatment applications, where it quickly eradicates Legionella and other microbes. It is widely used across NHS sites.
UV disinfection is a simple, low cost and popular method of water disinfection. UV systems expose water to light at just the right wavelength for killing microbes found naturally in water or water systems. They can be used to disinfect water in underground tanks, like those used in sports stadiums, before the water is drawn up for irrigation of playing services.
UV is an efficient way of killing bacteria, viruses, fungi, protozoans and cysts that may be present in water. However it does have its limitations as it can’t be used to remove gases, heavy metals and particulates, and bacteria can hide behind larger debris. This is why UV is often used in conjunction with other water disinfection methods.
Ozone is produced when oxygen is exposed to high-voltage current. It can be used to destroy viruses, bacteria and microbiology, and remove iron, sulphur and manganese from the water.
Ozone is a quick disinfection method and then rapidly decomposes, cutting down on the introduction of harmful disinfection by-products and foul tastes or odours associated with some chlorination processes.
Chlorine Dioxide (ClO2) production is a particularly effective microbiological control, Legionella control and primary and secondary water disinfection measure.
It requires generation (ClO2 cannot just be bought in a drum) and is suitable for biofilm eradication, membrane systems and filtration, water distribution systems, cooling towers, hospitals, hotels, horticulture, breweries, dairies and sites with hazardous chemical restrictions.
It’s sustained release effect means long-term stability in the water piping system, it has good conversion rates, and there is low risk of chemical handling. However, it is less effective in very hot water systems.
Learn more about water treatment techniques in our free ebook ‘Water safety, disinfection and secondary disinfection:
Determining the best solution for you will depend on a number of criteria, including your objective, how the water is used (e.g. drinking vs industrial), and flow rates.
In all likelihood, a combination of techniques will be required for your building or water distribution system.
For more information about water chemistry, water analysis, microbiology in water or to get your water or water distribution system tested and analysed in order to choose appropriate disinfection and water management, get in touch.