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Module 6 — Shock Chlorination
Signs of Nuisance Bacteria
There are a number of signs that indicate the presence of iron-related, sulfate-reducing
and other slime-producing bacteria. They include:
Slime growth
Rotten egg odor
Increased staining.
Slime Growth
The easiest way to check a well and water system for nuisance bacteria is to examine
the inside surface of the toilet flush tank. If you feel a greasy slime or growth, these are
probably present.
Rotten Egg Odour
Sulfate-reducing bacteria can cause a rotten egg odour in water. Iron-related bacteria
aggravate the problem by creating an environment that encourages the growth of SRBs in
the well. SRBs prefer to live underneath the slime layer that the IRBs form because they
thrive in low oxygen environments. SRBs produce hydrogen sulfide gas as a by-product,
resulting in a “rotten egg” or sulfur odour in the water and may produce small amounts
of acid that can corrode the well casing and pumping equipment.
Increased Staining Problems
Iron-related bacteria can concentrate iron in water sources with low iron content. It can
create a staining problem where one never existed before or make an iron staining problem
worse as time goes by.
Use the following checklist to determine if you have an iron-related or sulfate-reducing
bacteria problem. The first three are very specific problems related to these bacteria. The last
two problems can be signs of other problems as well.
Checklist to Determine an Iron-Related or
Sulfate-Reducing Bacteria Problem
Greasy slime on inside surface of toilet flush tank
Increased red staining of plumbing fixtures and laundry
Sulfur odour
Reduced well yield
Restricted water flow