Turbidity Tube

    Turbidity Tube

    Turbidity tubes are used when measuring the turbidity of streams.  Below are the steps involved when sampling in the field.  If you are using this tool at the edge of a pond, be sure to convert your measurement from centimeters (cm) to meters (m).




    Dip tube into the water at your sampling site and fill to the top. Be care to sample flowing water and not the stream bottom. Do not stand upstream from the area you are sampling.

    Filling tube

    Take the reading in an evenly lighted area.


    Cover your hand over the top and shake the tube to resuspend any sediment. 

    Look through the tube toward the target disk on bottom.

    If the disk is visible, record the water level in centimeters.

    read disk

    If the disk is not visible, slowly release water from the valve until the disk becomes visible and then stop the valve.

    If it takes awhile to do this and sediment covers the disk then cover your hand over the top and shake the tube to re-suspend any sediment.

    Cover with hand

    Once the disk is barely visible, record the water level in cm on your datasheet.

    You can then use this table to convert to NTUs.

    Record tube reading