Turbidity Data

Turbidity Data

The information on this page is intended for operators and owners of water systems that treat a surface water source to help them better understand the importance of turbidity data reported each month.

What is turbidity?

• Turbidity is a measure of water clarity. 
• High turbidity makes water appear cloudy or muddy. 
• Soil, silt, organic matter and microbes can all contribute to turbidity. 
• Turbidity is measured directly after filtration using a turbidity meter or sensor (nephelometry).  
• Results are reported in Nephelometric Turbidity Units (NTU). 
  

Why measure turbidity?

• Turbidity is used as an indicator of filter performance. 
• Removal of turbidity has been shown to be closely correlated to the removal of pathogens during filtration. 
• Pathogens such as Cryptosporidium are particularly resistant to chemical disinfectants, so optimal filtration is key to producing safe water. 
• To learn more about turbidity, see USEPA's Fact Sheet on Water Quality Parameters. 

Are there health risks?

• Turbidity has no health effects. However, turbidity can interfere with disinfection and provide a medium for microbial growth. 
• Turbidity may indicate the presence of disease-causing organisms. These organisms include bacteria, viruses, and parasites which can cause symptoms such as nausea, cramps, diarrhea and associated headaches. 

Viewing turbidity data

• View the turbidity data by water system name or identification number.
• In most cases, the turbidity shown will represent the maximum daily turbidity as measured from a point after filtered water from all filters combined prior to disinfection. 
  
• These results are referred to as the daily maximum combined filter effluent (CFE) turbidity.
  
• Some water systems may report the maximum individual filter effluent (IFE) turbidity when sampling from the CFE is not possible or the CFE sample location yields unreliable results (prior approval is required from OHA in these circumstances).

Clicking on the graph above will allow you to filter and view the data in a variety of ways. 

Whether reported as the maximum daily CFE or IFE NTU, the data is useful in helping operators identify problems and optimize treatment. 

Can I view compliance data?

• Turbidity requirements are specific to each filter plant facility and are referred to as Facility Analyte Levels (FANLs). 
• FANLs are regulatory limits like maximum contaminant levels (MCLs). 
• Compliance data is reported on standardized forms according to the applicable surface water treatment rule (SWTR), which are based on the type of filtration system. 
  
• Access Drinking Water Data Online
  
• Once in Data Online, you can look up a water system and use the links available towards the bottom of the main water system page to view FANLs & SWTR compliance reports or to view and download turbidity data. 
  
• Exceedances of regulatory turbidity limits (FANLs) should be reported to OHA as soon as possible as public notification is typically necessary.
• Turbidity exceedances are also required to be reported for community water systems in their annual Consumer Confidence Report. 
  

Are there optimal turbidity goals?

• Learn more about surface water treatment optimization goals and guidelines.  
• Learn how to minimize turbidity spikes in filter effluent turbidity. 
• Learn how to create a filter turbidity profile.

• Download the latest turbidity optimization spreadsheet.

 

View FANLs, SWTR reports, and turbidity data on Data Online