Turbidity is regulated under the secondary drinking water standard for aesthetic reasons and it is used as an operational control measure. Turbidity is commonly used as an indicator for the general condition of the drinking water, and is an easy field water-quality parameter to measure. Turbidity in water is caused by suspended matter such as clay, silt, and organic matter and by plankton or other microscopic organisms that interfere with the passage of light through the water (American Public Health Association, 1998). Turbidity is closely related to total suspended solids (TSS), but also includes plankton and other organisms. Turbidity of natural waters tends to increase during runoff events as a result of increased overland flow, stream flow, and erosion.
Turbidity, literally ‘dirty water,’ is the reduction of clarity in water due to the presence of suspended or colloidal particles. Turbidity is measured by the amount of light which is reflected by the particles back to a detector that is located at a 90 angle to the light path.
Water with a high turbidity may cause aesthetic problems (it looks dirty) and can damage fixtures, appliances, and piping. It can also make it more difficult to effectively treat a water source for other contaminants.
Turbidity itself is not a major health concern, however, high turbidity can interfere with disinfection and water treatment processes and provide a medium for microbial growth and contamination. A water with an elevated turbidity may be associated with aesthetic problems and nuisances.
The U.S. Environmental Protection Agency’s (EPA) Surface Water Treatment Rule requires systems using surface water or groundwater under the direct influence of surface water to (1) disinfect their water, and (2) filter their water or meet criteria for avoiding filtration so that at no time can turbidity go above 5 nephelometric turbidity units (NTUs). Systems that filter must ensure that the turbidity goes no higher than 1 NTU (0.3 NTU for conventional or direct filtration) in at least 95% of the daily samples in any month. Because of the potential association of elevated particles with bacterial or microbiological contamination and other nuisance issues, an elevated level of turbidity at the time of sample or post-sampling can suggest a water quality problem.
Unlike many contaminants in drinking water, the turbidity in itself is not potentially hazardous. An elevated water turbidity is used as an indicator of a water-quality-related problem that could include the presence of settleable and non-settable materials like sand, silt, or clay, iron, manganese, rust, biofilms, chemical scale or precipitates, or corrosion by-products. Your best course of action is to document the observable conditions or problems with the water and learn more about your source, well construction, surrounding land-use, household piping, existing water treatment systems and local geology. If you do have a turbidity problem, there are water treatment technologies available now that can reduce or even eliminate the turbidity problem of your drinking water.
Note: Do not just test your water for Turbidity because there may be other primary and secondary drinking water contaminants that could be elevated in the water or conditions in the system contributing to the problem. It is also possible that the suspended particles themselves, such as corrosion by-products, could be harmful.
Level 1 Testing is done with simple observations that an individual can make with their own senses such as sight, smell, and taste. These observations can be readily apparent or can be observed as they change over time. In addition, accessible related information about the home can also be used to narrow down the cause of your water issues.
The symptoms for turbidity in the water include:
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.
Turbidity can be associated with the presence of suspended particles, oxidized particles, biological films, and chemical coatings. At a minimum, we would recommend the Test Assured Complete In-home Water Screening Test and that you make sure you complete the Diagnostic Analysis in Level 1. If you conduct regular turbidity testing, we would recommend a turbidity meter. We routinely use either the Sper Scientific, LaMotte, or Hach Turbidity Meters.
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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.
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.
In order to evaluate a turbidity problem for potable water, it is necessary to understand the source of the water and have some basic information on the general water quality to please complete the diagnostic analysis. It is best to measure turbidity in the field and not in the laboratory.