Day 4: Chloroform

Chloriform is a contaminant that can form in water as the result of an interaction between chlorine disinfectants and organic matter – for this reason it is known as a disinfection byproduct.  Prolonged exposure can cause kidney and liver damage, and it can prove fatal in concentrations as low as 500 parts per million.


In 1897, the addition of chlorine to a water supply in Maidstone, England, ended a Typhoid outbreak, marking a new era in the chemical treatment of water, and a new era in public health.  By adding a disinfectant preemptively to a water supply, it became possible to eliminate microbiological contaminants, allowing people to drink water from a treated supply without fear of contracting diarrheal disease.  Chlorine remains the world’s most widely used disinfectant, however it is not without its drawbacks.  Interactions of chlorine with safe organic compounds can produce carcinogens – of which chloroform is but one – and this is why many countries prohibit the excessive use of chlorine in water treatment.

Further reading:

Leave a Comment