Colour
A measure of the visible colour of water, caused by dissolved organic matter, iron, manganese, or other substances.
ADWG Guideline
15 HU
Water colour is measured in Hazen Units (HU) or True Colour Units (TCU). It reflects the dissolved substances that tint the water — primarily natural organic matter (tannins and humic acids from vegetation), iron, and manganese.
Why it matters
The ADWG sets an aesthetic guideline of 15 HU. Coloured water:
- May indicate higher levels of natural organic matter, which can form disinfection byproducts when chlorinated
- Is generally not a direct health concern at typical levels
- Can stain laundry and affect the appearance of tea, coffee, and cooked foods
Difference from turbidity
Colour measures dissolved substances that tint the water. Turbidity measures suspended particles that scatter light. Water can be clear (low turbidity) but still coloured.
Check Your Water
See how colour levels compare in your suburb with real water quality data.
Disclaimer: Glossary definitions are provided for general educational purposes only and do not constitute medical advice or professional guidance. For specific health concerns about your drinking water, consult a qualified health professional. See our Terms of Use.