Access to safe drinking water is fundamental to public health, yet global water systems are increasingly under pressure.
Population growth, climate change, and infrastructure challenges are contributing to water scarcity and increasing the risk of waterborne disease in many parts of the world.
This post summarises research developed by our Technical Executive, Kaiya Edwards, as part of her distance learning programme with the University of Edinburgh. The research explores the relationship between water scarcity, pathogen transmission, and water disinfection technologies. It also reviews current scientific understanding of Chlorine Dioxide as a disinfectant and places its use within the broader context of global water treatment challenges.
Download the full research summary:
Chlorine Dioxide for Water Treatment and Sanitation
Global Water Scarcity and Public Health
Although around 75% of the Earth’s surface is covered by water, only a small proportion is accessible freshwater suitable for human use. Of the total global water supply, approximately 2.8% is freshwater, and only around 0.7% is readily available in surface and groundwater sources suitable for drinking water and sanitation systems.
The availability of safe drinking water has a direct influence on human health outcomes. According to international health data, large portions of the global population still lack access to reliable drinking water and sanitation infrastructure, increasing the risk of waterborne disease outbreaks.
Waterborne infections remain a major public health challenge in many regions. Pathogens can contaminate water supplies and cause significant illness and mortality if water treatment and sanitation systems are inadequate.
Effective water treatment therefore plays a critical role in reducing disease transmission and protecting communities.
Waterborne Pathogens and Biofilms
Many disease-causing microorganisms survive and spread through water systems by forming or inhabiting biofilms – complex microbial communities that attach to surfaces within pipes, storage tanks, and treatment infrastructure.
Biofilms provide microorganisms with protection from environmental stress and disinfectants, while also creating conditions that allow pathogens to persist within water distribution systems.
Examples of pathogens commonly associated with waterborne transmission include:
- Legionella pneumophila, responsible for Legionnaires’ disease
- Shigella species, which cause dysentery
- Cryptosporidium parvum, a parasite associated with gastrointestinal illness
- Vibrio cholerae, the bacterium responsible for cholera outbreaks
In many cases, these pathogens are transmitted through contaminated drinking water or poor sanitation infrastructure, particularly in regions where water systems are under stress due to environmental or economic factors.
Disinfection in Water Treatment
Water treatment processes aim to remove biological, chemical, and organic contaminants to ensure that drinking water is safe for consumption.
Disinfection is a critical stage in this process and can be achieved using several different technologies, including chlorination, Chlorine Dioxide, UV radiation, and thermal disinfection.
Chlorination has historically been the most widely used disinfection method due to its effectiveness and relatively low cost. However, reactions between chlorine and natural organic matter in water can lead to the formation of disinfection by-products such as trihalomethanes (THMs) and haloacetic acids, which have been associated with potential health concerns.
As a result, water utilities often evaluate alternative or complementary disinfection strategies depending on system design, regulatory requirements, and local water chemistry.
Chlorine Dioxide in Water Treatment
Chlorine Dioxide (ClO₂) is an oxidising disinfectant used in water treatment and sanitation applications.
Unlike chlorine, Chlorine Dioxide acts primarily through selective oxidation, disrupting microbial cell processes and damaging cellular components required for survival. This mechanism allows Chlorine Dioxide to inactivate a wide range of microorganisms at relatively low concentrations.
Because Chlorine Dioxide is unstable as a gas, it is typically generated on-site at water treatment facilities from precursor chemicals such as sodium chlorite.
The disinfectant is also effective across a relatively wide pH range (approximately pH 4–10), which can make it suitable for a variety of water treatment conditions.
Disinfection By-products and Regulation
Like all water treatment chemicals, Chlorine Dioxide must be carefully controlled to ensure regulatory compliance and safe drinking water quality.
During use, Chlorine Dioxide can form chlorite and chlorate, which are regulated in drinking water supplies. The World Health Organisation provides guidance values for these compounds to ensure that concentrations remain within safe limits for human consumption.
Water treatment systems using Chlorine Dioxide are therefore designed to carefully control dosing, generation, and monitoring to ensure compliance with regulatory standards.
Climate Change and Future Water Challenges
Climate change is expected to intensify pressures on global water systems by altering rainfall patterns and increasing the frequency of extreme weather events such as droughts and floods.
These environmental changes can increase the risk of water contamination and disease transmission, particularly in regions where water infrastructure is already under strain.
In response to growing water scarcity, many regions are investing in desalination and alternative water supply technologies. As of 2020, more than 20,000 desalination plants worldwide provide drinking water to hundreds of millions of people, particularly in water-stressed regions such as the Middle East.
Effective disinfection strategies remain a critical component of ensuring that these water supplies remain safe for human consumption.
Continuing Research and Collaboration
Addressing global water challenges requires collaboration across engineering, environmental science, microbiology, and public health disciplines.
The research summary linked above was developed as part of a postgraduate distance learning programme with the University of Edinburgh and provides an overview of current scientific understanding surrounding water scarcity, pathogen control, and disinfection technologies.
At Scotmas, we recognise the importance of ongoing research, professional development, and engagement with academic institutions in supporting evidence-based approaches to water treatment.
Download the full research summary:
Chlorine Dioxide for Water Treatment and Sanitation
