What is Turbidity?

We used to think that turbidity (cloudiness or particles in water) was just an aesthetic concern. Now science has shown that as turbidity rises, the risk of gastrointestinal illness increases as well. While this might not be a concern for most of us, the risk for the very young, the very old, and people with weakened immune systems can be higher. As a result, more is being done to provide information about turbidity so people can make informed choices about their drinking water.

To help our customers, particularly those most at risk from waterborne illness, water suppliers have partnered with Interior Health to create the Turbidity Education & Notification Campaign. The campaign is designed to educate users about turbidity and notify them of elevated turbidity levels. The heart of the campaign is the Turbidity Index, a user-friendly tool that shows whether water is Good, Fair, or Poor. You now can check daily the Turbidity level that is recorded each day by Lakeview Irrigation District.

Some interesting facts:

Turbidity is caused by fine suspended particles of clay, silt, organic and inorganic matter, plankton, and other microscopic organisms that are picked up by water as it passes through a watershed. While turbidity usually results from natural events such as spring runoff, it can also be caused by manmade erosion.

Turbidity — reported in nephelometric turbidity units (NTU) — is an optical measurement of water’s ability to scatter and absorb light rather than transmit it in straight lines.

Turbidity levels are typically much higher in water from surface sources than in groundwater. Turbidity levels can range from less than 1 NTU to more than 1,000 NTU. At 5 NTU water is visibly cloudy, and at 25 NTU it is murky.

Turbidity was once considered only an aesthetic concern. But science has proven that as turbidity increases, the risk to human health also increases, particularly for at-risk populations such as newborns, the elderly, and the immunocompromised. Turbidity is an important good water quality indicator because bacteria, viruses, and parasites such as Giardia and Cryptosporidium can attach themselves to the suspended particles in turbid water. These particles interfere with disinfection by shielding contaminants from the disinfectant (e.g. chlorine). Nor is chlorine effective in deactivating Cryptosporidium. To support its statement that the “control of turbidity in drinking water supplies is important for both health and aesthetic reasons,” the federal Guidelines for Canadian Drinking Water Quality state that “the maximum acceptable concentration of turbidity in water entering a distribution system is 1 NTU.” The guidelines were recently updated to recommend filtration for all surface water sources.