08. Debate

The Great Chemistry Debate May 2026 

The Issue of Chlorination of our municipal waters 

In the modern world, almost all of us take clean water for granted. However, as with so many of our basic resources, providing clean water is not a simple endeavor. Behind every glass, there is a fascinating and complex process, one that keeps people healthy. Elimination of pathogens that impact our environmental health is critical to this end. The best-known and widely used water disinfection method worldwide is chlorination. Chlorination is used for drinking water supplies and as part of the treatment of wastewater. Chlorination adds chlorine compounds to wastewater that produce “free chlorine,” which destroys pathogens by damaging cell membranes, disrupting cellular respiration, and rendering enzymes non-functional. Chlorination remains popular due to its effectiveness, reliability, and cost-efficiency. 

There are concerns, however. Although chlorination is a critical public health practice using chlorine to kill germs and prevent waterborne diseases like cholera, under certain circumstances it can  create disinfection byproducts (DBPs) like THMs and HAAs that are linked to long-term health risks, including potential cancer and respiratory issues,  These concerns have been raising ongoing debates about balancing disinfection benefits with DBP exposure, especially for vulnerable populations,  Utilities monitor levels and homeowners use filtration to reduce taste, odor, and potential risks, but questions remain.  

The question: Should chlorination of water and wastewater in municipal systems be mitigated, restricted or banned in the US? Consider the following: 

Background: 
Chlorine has been used for over a century to disinfect drinking water and prevent diseases like cholera. However, it reacts with natural organic matter to form disinfection byproducts (DBPs) like trihalomethanes, some of which are carcinogenic. Alternatives include ozonation and UV treatment among others. 

Pro (Phase out chlorine): 

Con (Keep chlorine use): 

Chemistry Focus: Oxidation reactions, halogen chemistry, formation of disinfection byproducts. 

Part 1 – Conduct general literature research on the issue: 

 The essay should address: 

Part 2 - Each team: 

Will be randomly assigned either the YES or NO position by the judges. 

Each team must present their assigned position (YES or NO) on the question in a 3 - 5 minute oral presentation, optionally with the ONE slide they prepared on that position 

The Judges will ask each team one question about this initial presentation.   Each team will take two minutes to address their question from the Judges. 

Each team will ask another team one question (previously submitted by their team) to be answered in one minute, after two minutes of deliberation by the answering team.