Colorimetric Test
A colorimetric test measures water chemistry by observing the colour change of a reagent added to a water sample.
Definition
A colorimetric test measures water chemistry by observing the colour change of a reagent added to a water sample.
Typical Values: Best read in natural light or bright white light; compare immediately after adding reagents
In Plain Language
All standard liquid pool tests (DPD, phenol red, etc.) are colorimetric tests — they rely on colour comparison between a treated sample and a reference standard. The colour intensity or shade corresponds to the concentration of the measured parameter. Colorimetric tests can be read visually (using a comparator block) or quantitatively with a photometer, which measures light absorbance through the sample rather than relying on human colour perception.
Why It Matters
Understanding colorimetric testing helps users recognise why lighting conditions, reagent age, and technique affect result accuracy.
Typical Values
Best read in natural light or bright white light; compare immediately after adding reagents
Last reviewed: 2026-06-01