Microbiological Analysis
 
The most important contaminant in water is disease-causing microorganisms. All water contains
some microbes that normally live in lakes and streams, and in the ground. These organisms rarely
cause health problems. However, if water is contaminated with human or animal waste, danger-
ous microbes can enter the water supply.
 
Fecal Coliform Test or E. coli
All of our packages include at least one test for the presence of E. coli or fecal coliforms.
These organisms are only found in human and animal waste. While they may not be dangerous
by themselves, they indicate that a water supply is contaminated. If your water fails this test, you
should not use it without treatment. Common sources of contamination are inadequate septic
systems and uncontrolled livestock waste. However, this sort of bacteria can also get into your
water supply from dirty fixtures, or back-flow from irrigation or animal watering systems. [More
information]
 
Total Bacteria
Our more advanced packages include the “heterotrophic plate count,” which is an esti-
mate of “total” bacteria in water. Actually, it counts bacteria that are likely to grow in common
food items. These bacteria are not likely to be harmful, but high numbers can lead to rapid food
spoilage, and may be harmful to those with weakened immune systems. [More Information]
 
Iron Bacteria
Some bacteria metabolize the different forms of iron, and can contribute to corrosion and
iron-staining in your plumbing system. Tests for Iron Bacteria are included in the “Ultimate” pack-
age and can be added to any other package by selecting “additional microbial tests,” and
choosing them from the microbe menu.
 
In general, there are two kinds of “iron bacteria.”
Iron-reducing bacteria use ferric iron (rust) in the same way that humans use oxygen. If these
bacteria grow in your water system, they can cause slime buildup and off-flavors. However, they
can only grow if your water lacks oxygen and contains excess organic matter. Oil-filled pumps
are a likely habitat for these organisms.
Iron-oxidizing bacteria use ferrous iron in the same way that humans use food. This kind of iron is
dissolved in some groundwater or can come from corrosion of iron pipes. These organisms often
grow in plumbing systems where anoxic groundwater mixes with air.
 
Sulfur Bacteria
Some bacteria metabolize different forms of sulfur. Sulfate-reducing bacteria can produce
rotten-egg smells and cause corrosion of metal and concrete. Sulfur-oxidizing bacteria can cre-
ate slime layers in pluming and produce off-flavors. Assays for these organisms are included in the
“Ultimate” package and can be added to any other package by selecting “additional microbial
tests,” and choosing them from the microbe menu.
What to do about it?