Field tests are considered the only accurate method for measuring which pollutant?

Field tests are particularly important for measuring chlorine residual because they provide real-time results that are essential for ensuring the effectiveness of disinfection processes in water treatment facilities. Chlorine residual is a key indicator of whether the chlorine used to treat water is still present at the required levels, which is crucial for controlling pathogens and maintaining water quality.

In the field, testing for chlorine residual allows operators to quickly adjust chemical dosing and respond to any potential contamination issues. Laboratory methods may involve more complex procedures and longer wait times, leading to potential delays in reacting to water quality changes.

While other pollutants can be measured through field testing as well, the immediacy and accuracy required for chlorine residual, especially in ongoing disinfection processes, highlight the necessity of these field tests.