There are a variety of bacteria, parasites, and viruses which can cause health problems when humans ingest them in drinking water.
Testing water for each of these germs would be difficult and expensive. Instead, water quality and public health workers measure for the presence of bacteria in dinking water using coliform bacteria as an indicator.
* Indicator, I see...
The presence of any coliforms in drinking water suggests that there may be disease-causing agents in the water.
* More extensive testing starts...
The Total Coliform Rule (TCR), which was published in 1989, set both health goals (MCLGs) and legal limits (MCLs) for the presence of total coliforms in drinking water.
* How about PMEU?
The rule also details the type and frequency of testing that water systems must undertake. The rule applies to all public water systems.
This site provides information about microbial pathogens and disinfection byproducts as related to drinking water.
In many cases, source water from a lake, river, reservoir or ground water aquifer needs to be disinfected to inactivate (or kill) microbial pathogens.
Microbial pathogens include a few types of bacteria, viruses, protozoa, and other organisms. Some pathogens are often found in water, frequently as a result of:
- Fecal matter from sewage discharges
- Leaking septic tanks
- Runoff from animal feedlots into bodies of water
To protect drinking water from these pathogens, water suppliers often add a disinfectant to drinking water such as chlorine. However, disinfectant practices can be problematic because:
- Certain microbial pathogens, such as Cryptosporidium, are highly resistant to traditional disinfection practices.
- Disinfectants themselves can react with naturally-occurring materials in the water to form byproducts, such as trihalomethanes and haloacetic acids, which may pose health risks.
A major challenge for water suppliers is how to balance the risks from microbial pathogens and disinfection byproducts. It is important to provide protection from microbial pathogens while simultaneously minimizing health risks to the population from disinfection byproducts.
There are several existing and future rules that are designed to achieve these goals.
This web site is designed to provide you with information about microbial pathogens, disinfection byproducts, existing and future rules, as well as guidance materials and background information."