Turbidity Explained

by Reid Burns in

What is turbidity?

Turbidity is the the measurement of water clarity. It is measured by looking at the amount of light that is allowed through a sample of water. Clear water has low turbidity and murkier water has higher turbidity.

Turbidity and Total Suspended Solids (TSS) many times get confused. They are different, but related. TSS are the actual particles in the water, while turbidity is the amount of light that gets past those particles (measure of water clarity). More TSS usually means more turbid water.

What causes turbidity?

Turbid water can be caused by many different sources. Listed below are some of the common causes of turbidity:

  • Dirt
  • Silt
  • Organic matter
  • Bacteria
  • Pathogens
  • Microscopic organisms
  • Plant particles
  • Plankton

How do the above items get into the water? Well most of the time it has to do with human activity. Common events and activities (some of which we help treat before the water makes it to the environment) that can cause higher turbidity are:

  • Rain / Storms
  • Snowmelt
  • Erosion
  • Mining
  • Construction
  • Waste runoff
  • Chemical runoff
  • Fertilizer runoff
  • Food processing
  • Urban runoff
  • Other wastewater

Untreated wastewater is one of if not the biggest cause of turbidity levels rising in all bodies of water around the world. View our case studies page to learn how we help clean wastewater in many different industries.

How do you measure turbidity?

Optoelectronic meters are used to measure a water sample's turbidity. These systems work by shooting a known level of light (either white light or infrared light) through a water sample. The light then is scattered based on the water's clarity (or turbidity) and measured giving us the turbidity levels. These meters can also be called "nephelometers."

For low cost educational settings water test kits are available from World Water Monitoring Challenge.

A unit of turbidity measurement is a Nephelometric Turbidity Unit (NTU). The more the light is scattered or blocked during testing the higher the turbidity. Turbidity should ideally be under 1 NTU for drinking water.

Is turbidity or cloudy water dangerous?

High turbidity in drinking water does not look right, and may also cause health issues for anyone who drinks that water. Many times (just like in nature above) more turbidity allows pathogens to grow in the water. It allows these microorganisms to feed and shelter from direct sunlight and other disinfectants, which would kill them. The systems we build and your town uses to clean your drinking water should help remove turbidity completely so this is not a worry of yours. At the end of the day it is not always the turbidity that is the cause of concern in drinking water, but many times that something else could be hiding within.

High turbidity out in the environment is also dangerous for ecosystems and many animal species. The cloudy water can cause diminished food supplies for fish and other aqua based creatures. The particles in the water can also cause the fish to get sick, not grow as large, impact spawning grounds, impact fertility, and more.

Have an industrial or municipal turbidity problem? Reach out to our team of process engineers today!


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