Colour of Water Testing Kits

  • Handheld Colorimeter
  • Easier to use and more accurate than chemical test kits
  • Dedicated to a single parameter
  • Small size, big convenience
  • Ideal for water quality

True colour is caused by dissolved compounds in water and can be both natural or artificial. Apparent colour is caused by both dissolved and suspended solids. Colour is measured in Platinum-Cobalt units (PCU). The AWWA recommends ≤ 15 PCU.

The term ‘‘true colour’’ is defined as the colour of water from which turbidity has been removed. The term ‘‘apparent colour’’ includes not only colour due to substances in solution, but also colour that is due to suspended matter. Apparent colour is determined on the original sample without filtration or centrifugation. In some highly-coloured industrial waste waters, colour is contributed principally by colloidal or suspended material. In such cases, both true colour and apparent colour should be determined.

To determine true colour, turbidity must be removed before analysis. Methods for removing turbidity without removing colour vary. Filtration yields results that are reproducible from day to day among laboratories, however, some filtration procedures may also remove some true colour. Centrifugation avoids interaction of colour with filter materials, but results vary with the sample nature, size, and speed of the centrifuge. When sample dilution is necessary, whether it precedes or follows turbidity removal, it can alter the measured colour. Acceptable pretreatment procedures are included with each method. The pretreatment method should be stated when reporting the results.

The HI727 Checker®HC is very simple to use. First, zero the instrument with deionised water. Next, prepare the sample according to the Apparent/True colour measurement. Place the second vial with prepared sample into the Checker®HC, press the operational button and the HI727 Checker® displays the colour of water in PCU.

Range0 to 500 PCU
Resolution5 PCU
Accuracy @ 25°C/77°F±10 PCU ±5% of reading
Light SourceLED @ 470 nm
Light Detectorsilicon photocell
Environment0 to 50°C (32 to 122°F); RH max 95% non-condensing
Battery Type(1) 1.5V AAA
Auto-offafter ten minutes of non-use
Dimensions81.5 x 61 x 37.5 mm (3.2 x 2.4 x 1.5”)
Weight64 g (2.25 oz.)
Methodadaptation of the Standard Methods for the Examination of Water and Wastewater, 18th edition, Colorimetric Platinum Cobalt method

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