Enter your Turbidity Value, select your Input Unit (NTU, FTU, JTU, and more), and choose a Convert To unit to get your Converted Turbidity reading — plus a Water Clarity Assessment and plain-language Description of what that cloudiness level actually means.
Converted Turbidity
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Water Clarity Assessment
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Description
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Turbidity measures the cloudiness or haziness of water caused by suspended particles. It's crucial for water quality assessment as high turbidity can indicate contamination and affect disinfection effectiveness.
NTU (Nephelometric Turbidity Units) is the EPA standard, FTU (Formazin Turbidity Units) uses formazin as reference, and FNU (Formazin Nephelometric Units) follows ISO 7027 standards. They measure similar properties but with different methodologies.
The EPA requires treated drinking water to have turbidity levels below 1 NTU, with an optimal target of 0.3 NTU or lower. Raw water sources typically range from 0.1 to over 1000 NTU.
Turbidity tubes use inverse relationships - shorter tube readings indicate higher turbidity. For example, a 6-8 cm reading corresponds to about 150-240 NTU, while readings over 60 cm indicate very clear water below 6 NTU.
High turbidity results from suspended particles like sediment, soil, organic matter, algae, and microorganisms. Sources include erosion, agricultural runoff, construction activities, and natural organic decomposition.
Common methods include nephelometric sensors (most accurate), turbidity tubes, Secchi disks, and historical Jackson candle methods. Modern optical sensors following EPA 180.1 or ISO 7027 standards provide the most reliable measurements.