True color is caused by dissolved compounds in water. It can be natural or artificial. Dissolved and suspended solids (together) cause apparent color. Color is measured in Platinum-Cobalt units. The AWWA recommends ≤ 15 PCU.
The HI 727 Checker®HC is extremely simple to use. First, zero the instrument with deionized water. Next, prepare the sample according to the Apparent/True color measurement. Place the second vial with prepared sample into the Checker®HC, press the operational button and the HI 727 Checker®HC displays the color of water in PCU.