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Get Informed | Nuisance Bacteria

What are Nuisance Bacteria?

In drinking water, the common group of bacteria that has been described as potentially nuisance bacteria, include: Iron Bacteria, Slime Bacteria, Sulfate-Reducing Bacteria, standard plate count or heterotrophic bacteria (HPC), and pink bacteria. For the record, Pink Bacteria are not waterborne bacteria, but airborne bacteria that happen to grow in damp areas like bathroom tubs, showers, and toilets.

How Do Nuisance Bacteria Become a problem?

With the exception of a standard for standard plate count, these bacteria are not specifically regulated by a drinking water standard. However, their growth can create situations or problems that can result in the violation of a primary or secondary drinking water standard. Therefore, I tend to call these types of organisms nuisance bacteria, because they tend to create a nuisance problem before they create or facilitate a problem associated with a health concern or impact.

Slime bacteria are a group of bacteria that produce slime, but unlike iron bacteria they do not need to use iron or manganese in the process. The slime produced by slime-forming bacteria is typically gray, clear, and thicker than iron-related bacteria, but they can appear yellow or beige if other metals accumulate in the polysaccharide polymer slime layer. When the organism is stressed, it can create a thicker slime layer, something that is also promoted under aerobic conditions.

Iron-related bacteria that reduce iron or manganese (electron donors) to get energy, are called chemotrophs. These non-pathogenic (non health-threatening) bacteria occur in soil, shallow aquifers, and some surface waters.

Sulfate-related or reducing bacteria obtain energy by using a carbon source to reduce sulfate to hydrogen sulfide gas. Typically, these bacteria become established after the oxidizable oxygen, nitrate, iron, and manganese have been used up by other bacteria. For many water systems, the presence of this type of bacteria suggests a long-term microbiological problem with the water and not a short-term or recent condition.

What are the Health Risks for Nuisance Bacteria?

We would have to say that there are no direct health risks, however, they are indicators of a potential health risk from other bacteria or microbiological agents. Ineffective disinfection of these bacteria can create conditions that result in increased or elevated levels of trace metals, such as: copper, lead, chromium, aluminum, and zinc. We have also seen a few cases where these bacteria appeared to be opportunistic pathogens for individuals under health stress or with a compromised immune system (Source).

What are the Standards for Nuisance Bacteria?

With the exception of a standard plate count, there are no specific standards for nuisance bacteria. In 1989 the EPA set a non-health specific standard for standard plate count at a level of 500 colonies per ml and was proposing the use of this bacteria as a surrogate for total coliform bacteria. (Source) Standard plate count or HPC is commonly used in the bottle water industry and we tend to use this test as a surrogate for bacterial regrowth in distribution systems. We have found that increasing and elevated levels of HPC are associated with bacterial regrowth in the distribution system, increasing chlorine or oxidant demands within distribution systems, the likely presence of nuisance odors, and localized biochemical/chemical corrosion.

Some nuisance bacteria can create additional nuisances or conditions that can result in violating a primary or secondary drinking water standard. In most cases, the primary drinking water standard violations are related to the presence of metals associated with the plumbing and plumbing fixtures in the home or building or possibly an increased level of phthalates, because the bacteria use them as a carbon source. (Source)

Get Tested | Nuisance Bacteria

Nuisance bacteria do create warning signs, but this commonly does not occur until the bacterial population gets high enough to create a problem the average person could smell, see, taste, or some other effect that is a "nuisance". You must be willing to look and take note of these early warning signs. In addition to nuisance issues, these bacteria can clog pipes and filters, cause premature failure or more frequent maintenance of water-using appliances and heat-exchange units, can cause a decrease in the pumping efficiency or yield of a water well, and be associated with intermittent odors, discolored water, and "off taste" to your drinking water. Nuisance bacteria can be a problem with all drinking water sources, even City Water.

Level 1 | Observational Self-Testing

Observations for Nuisance Bacteria

You should check for the presence of a bacterial nuisance under the following conditions:

  • The water creates a nuisance, such as: an off-taste, discolored water, or odors
  • The surfaces of the piping, plumbing fixtures, filters, or insides of basins have slimy or biological films or coatings
  • Stagnant water or standing water has a metallic sheen
  • You are experiencing discolored water that includes the following colors: blue-green, blue, green, yellow, red, black, and brown.
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Have water issues? Answer our self-diagnosis questionnaire from your observations to get an initial diagnosis. Then follow our recommended steps to remediate your issue.
Self-Diagnostic Tool

Level 2 | Do-It-Yourself Water Testing

Level 2 Testing is Do-It-Yourself testing that can be done in your own home using a Testing Kit. After you’ve done Level 1 Testing, Level 2 Testing can confirm if your observations are correct. If your test results reveal the presence of a contaminant that is cause for concern, you can either proceed to determine the best treatment (see below) or continue to Level 3 Testing.

Notes on Level 2 Testing for Nuisance Bacteria

Most in-home water test kits are not designed for nuisance bacteria, but most kits are designed to test for the presence of total coliform and E. coli. The first step is to conduct a basic in-home water quality test for bacteria.  If you have a sulfur odor, we also recommend the Sulfate-Reducing Bacteria Testing, but if you see slimy reddish, black, or brown films with little to no odor, but water with a metallic sheen, we also recommend testing for the Iron-Related Bacteria.

Level 3 | Informational Water Testing

Level 3 Testing is done through an accredited Water Testing Laboratory. With Level 3 Testing, you can order a testing kit that is used to prepare your sample and submit it to the lab. By utilizing a lab, you have the assurance that a certified water expert had analyzed your water sample. If your test results reveal the presence of a contaminant that is cause for concern, you can either proceed to determine the best treatment options (see below) or continue to Level 4 Testing - Certified Testing.

Notes on Level 3 Testing for Nuisance Bacteria

The selection of the best laboratory screening test depends on your observations. If you are concerned about the general bacterial quality of the water and do not have a specific observable problem, we recommend the Quick Bacteria Test.  If you have an observable problem that is associated with a reddish or black water with some odor that is not sulfur-like, we recommend the Problem Check Iron Bacteria Test.  If you have a sulfur odor, we recommend the sulfate-related bacteria test.  If you suspect a waterborne pathogen, we suggest the total microbiological test.  If you suspect Legionella, we suggest the total microbiological test and the Legionella test.  If you suspect Giardia or Cryptosporidium, we suggest the total microbiological test and the Giardia/Cryptosporidium test offered by Tap Score.

Professionals: You many want to consider conducting ATP Bio-Contamination Testing testing of some of the interior surfaces of the piping.

Level 4 | Certified Water Testing

A Level 4 Certified Test Test uses chain-of-custody with a water professional coming to your home to prepare the water sample and then works with an accredited laboratory in order to certify your test results. This type of testing not only gives you the highest level of assurance in the accuracy of your test results, but can also be used as a document in legal cases. For Baseline Testing, we recommend that you use Certified Testing.

Notes on Level 4 Testing for Nuisance Bacteria

If you identified or think there might be a bacterial problem, we suggest certified testing to document the actual number of colony forming units. Typically, this is best done using a local certified laboratory, because the holding time and sampling requirements have a very short holding time.

Get Treatment | Nuisance Bacteria

If you are using a private well, we recommend shock disinfecting the well and distribution system twice and, if necessary, installing a sanitary well cap and securing the wellhead. Securing the wellhead means, the top of the well casing is 18 inches above grade and above flood level, the cap has a screen to prevent entry of vermin or insects (Sanitary Well Cap), surface water does not pond in the vicinity of the wells, and water is not seeping into the well along a pitless adapter or through the cased zone because of a bad joint, faulty weld, or a corroded casing. In some cases, a well might not have adequate casing to seal off near-surface contamination in which case the well needs to be lined or abandoned and a new well drilled. After the wellhead has been secured, the water from the well should be tested at two locations, at a tap near the well and at the far end of the distribution system. Various types of disinfection systems may include submicron-nanofiltration, chlorination, ozonation, peroxide addition, and UV irradiation.

If you are on a city water system that is disinfected, our primary recommendation is to contact your water supplier and report any aesthetic issues, results of any screening tests, including tests of the level of chlorine or disinfection residual in your water. For some homeowners, we recommend installing a filter housing so you can shock disinfect and flush the piping in your home. In a few cases, we have recommended the installation of a 5 to 20 micron particle filter and a Class B UV disinfection system to polish the drinking water and to provide a final barrier.

Short-Term Treatment

In the short term, you could use an alternative water source for consumption and/or boil the water prior to consumption. When boiling your drinking water, we recommend a rolling boil for at least 3 minutes. For well water and spring water users, it may be wise to chemically treat the well or spring box with an NSF approved product (Well-Safe C21000 Well Sanitizer Pack) to "shock disinfect" the well and distribution system. We do not recommend using "household bleach" to shock disinfect systems unless it is related to an "emergency" because it can contain other contaminants and by-products. For city water users, it may be wise to flush your water lines in the home to increase the level of chlorine, pasteurize your water-heating tanks, and to notify the city of your issues so they can consider flushing the main. If you are using a water well or spring box, you may need to hire a contractor to chemically treat the well to address the combination of bioslimes, biological organisms, and associated chemical scale.The solution to the problem may be regular cleaning and maintenance and not installing a treatment system. The well may need some rehabilitation.

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Long-Term Treatment

The long term solution will depend on the water quality and the level and type of bacterial contamination. If the water is only contaminated with total coliform bacteria and is E. coli. negative, it may be possible to install a 5 to 20 micron whole-house particle filter and a Class B UV disinfection system. If the water is total coliform and E. coli. positive and you do not suspect viruses or protozoans, it may be possible to install a 5 to 20 micron backwashable particle filter and a Class A UV disinfection system. We recommend using a UV disinfection system that would meet NSF /ANSI 55 Standards. For UV disinfection, either sediment filtration or activated carbon filtration should take place before water passes through the unit. Particulate matter, color, and turbidity affect the transmission of UV to the microorganisms and must be removed for successful disinfection.

Class A point-of-entry and point-of-use systems covered by NSF /ANSI 55 are designed to inactivate and/or remove microorganisms, including bacteria, viruses, Cryptosporidium oocysts and Giardia cysts, from contaminated water. These systems are not intended for the treatment of water that is obviously contaminated by sources such as raw sewage, nor are these treatment systems intended to convert wastewater to drinking water. The systems are intended to be installed on visually clear water. Class A- UV sterilizers that meet NSF/ANSI Standard 55 Class A are required to provide a UV dose in excess of 40 mJ/cm2 over the entire life of the UV lamp and to monitor the UV output and flow restriction to control the rate of flow through the unit.

Class B — These ultraviolet water treatment systems must have an ‘intensity & saturation’ rating of at least 16,000 uw-sec/cm2 and possess designs that will allow them to provide supplemental bactericidal treatment of water already deemed ‘safe’. i.e., no elevated levels of E. coli. or a standard plate count of less than 500 colonies per 1 ml. NSF Standard 55 "Class B" UV systems are designed to operate at a minimum dosage and are intended to "reduce normally occurring non-pathogenic or nuisance microorganisms only." The "Class B" or similar non-rated UV systems are not intended for the disinfection of microbiologically unsafe water. This unit should only be used on water that has already been disinfected and only additional or supplemental treatment is needed or on water that meets the potable water supply standards.

Other common disinfection methods would be chlorination using a dry-tablet erosion-chlorination system or chlorine feed system. To a lesser extent, ozone and peroxide have been used to disinfect water. Depending on the source water quality, it is possible for these stronger oxidizers to react with natural-occurring organics and bromide to create disinfection by-products. Because of the need for reaction time to permit the disinfection to occur and to remove any disinfection by-products, these systems normally include some time-of-reaction in a holding tank and post filtration using granular-activated-carbon.

In many cases, the first action should be to identify the cause and the type of bacteria causing the problem. The long-term solution may require a modification to the well or spring box or other water source to reduce the vulnerability of the source to contamination. If you only deal with the results of the "uncontrolled bacterial growth", the growth in the well or spring box will ultimately decrease the well or spring yield and over time cause the water to continue to degrade. At some point, the treatment system will no longer operate properly. For many of these cases with well water sources, the long-term solution included hiring a well drilling contractor and a water treatment specialist. If you need help, Contact our team.

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