Principle

Water colour is measured in Hazen Units (HU), and is a measure of the cleanness of the water source. Distilled water should have a colour of 0 HU.

The Indian Standard for drinking water holds that the acceptable limit is 5 Hazen Units, but in the absence of any other toxic substances or alternate source, this is relaxable upto 15 Hazen Units.

Calibration

To prepare calibration standards, take 20 ml of distilled water. Depending on if you chose minimal or full calibration, prepare standards as below.

Full Calibration

Standard Drops
0 HU 0
25 HU 10
50 HU 20
100 HU 40

Minimal Calibration

Standard Drops
0 HU 0
50 HU 20
100 HU 40

You do not need to add any reagent for this test.

  • Take the 0 standard and fill it into the cuvette. In this case you will need to add the standard to the tall glass tube, and place it into the white cuvette.
  • Place the cuvette under the light box and turn it on.
  • Place the phone over the stand.
  • Go to Settings > Colorimetric Test > Calibrate > Water and choose Hazen Units.
  • Select the calibration point, 0.00 HU in this case.
  • Click on Start Camera.
  • Position the cuvette so that the middle, most uniformly lit portion is within the circle.
  • Select Analyze.
  • You should have your first calibration point. Repeat similarly with the other calibration points.

Test

This test does not require a reagent.

  • Collect 20 ml of sample water and place in cuvette. In this case you will need to add the sample to the tall glass tube, and place it into the white cuvette.
  • Place the cuvette under the light box and turn it on.
  • Place the phone over the stand.
  • From the home screen choose Colorimetric Test > Water > Hazen Units.
  • Choose No Dilution if this is the first test, you might have to dilute the sample and retry later if you get an error.
  • Click on Start Camera.
  • Position the cuvette so that the middle, most uniformly lit portion is within the circle.
  • Select Analyze.
  • After some time, the app will display a result.