Color chart, test kit, and method for determining chemical oxygen demand of water and wastewater

The present invention provides a color chart and a test kit for determining chemical oxygen demand of water and wastewater. The color chart includes a blue component, an indigo component, an umber component, and an orange component. The test kit includes an oxidant, a reductant, an indicator, and the color chart. The present invention also provides a method for determining chemical oxygen demand of a water and/or wastewater sample. The method encompasses providing a water sample; adding an oxidant into the water sample; heating the water sample; adding a reductant into the water and/or wastewater sample; adding an indicator into the sample, and thereby the water/wastewater sample has a color; and matching the color of the water/wastewater sample with the color components of the color chart to determine the chemical oxygen demand of the water and wastewater sample.