Water Quality Glossary
Understand the terms used in Australian water quality reports. From pH and hardness to PFAS and ADWG guidelines — plain-English definitions for every metric.
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Measurements & Properties
Contaminants & Metals
Treatment & Disinfection
Standards & Regulations
Units of Measurement
All Terms A–Z
A
- ADWG (Australian Drinking Water Guidelines)
- The national guidelines published by the NHMRC that set quality standards for Australian drinking water.
- Alkalinity (mg/L CaCO3)
- A measure of water's capacity to neutralise acids, primarily from dissolved bicarbonate, carbonate, and hydroxide ions.
- Aluminium (mg/L)
- A metal that can enter treated water from aluminium-based coagulants used in water treatment.
C
- Calcium (mg/L)
- An essential mineral and major contributor to water hardness, dissolved from limestone and other geological formations.
- Chloramine (mg/L)
- A longer-lasting disinfectant formed by combining chlorine with ammonia, used in some Australian water supplies.
- Chloride (mg/L)
- A mineral ion that affects the taste of water and can indicate saltwater intrusion or contamination.
- Chlorine (mg/L)
- A disinfectant added to drinking water to kill harmful bacteria, viruses, and other pathogens.
- Colour (HU)
- A measure of the visible colour of water, caused by dissolved organic matter, iron, manganese, or other substances.
- Conductivity (uS/cm)
- A measure of water's ability to conduct electricity, which indicates the total concentration of dissolved ions.
- Copper (mg/L)
- A metal that can dissolve into water from copper plumbing, especially in new homes or where water is acidic.
D
- Disinfection Byproducts
- Compounds that can form when disinfectants such as chlorine react with natural organic matter in source water.
- Dissolved Oxygen (mg/L)
- The amount of oxygen gas dissolved in water, important for aquatic life and an indicator of water quality.
E
- E. coli (MPN/100mL)
- A bacterium used as an indicator of faecal contamination in drinking water. Its presence suggests a potential risk from harmful pathogens.
F
- Fluoride (mg/L)
- A naturally occurring mineral added to most Australian water supplies to prevent tooth decay.
H
- Hardness (mg/L CaCO3)
- The concentration of dissolved calcium and magnesium minerals in water, measured in mg/L as calcium carbonate.
I
- Iron (mg/L)
- A naturally occurring metal that can cause orange-brown discolouration, staining, and a metallic taste in water.
L
- Lead (mg/L)
- A toxic heavy metal that can leach into drinking water from old pipes, solder, and fittings.
M
- Magnesium (mg/L)
- An essential mineral that contributes to water hardness alongside calcium.
- Manganese (mg/L)
- A naturally occurring metal that can cause black staining and discolouration in water at elevated levels.
- mg/L (Milligrams per Litre)
- The most common unit for measuring dissolved substances in water — equivalent to parts per million (ppm).
N
- Nitrate (mg/L)
- A nitrogen compound that can enter water from agricultural runoff, fertilisers, and septic systems.
- NTU (Nephelometric Turbidity Units)
- The standard unit for measuring turbidity (cloudiness) in water.
P
- PFAS
- Per- and polyfluoroalkyl substances — a large group of synthetic 'forever chemicals' that persist in the environment and can contaminate water supplies.
- PFOA (ug/L)
- Perfluorooctanoic acid — a PFAS compound formerly used in manufacturing non-stick coatings and waterproof fabrics.
- PFOS (ug/L)
- Perfluorooctane sulfonate — one of the most studied PFAS compounds, formerly used in firefighting foam and stain-resistant coatings.
- pH (pH units)
- A measure of how acidic or alkaline water is, on a scale from 0 (acidic) to 14 (alkaline).
R
- Reverse Osmosis
- A water filtration method that pushes water through a fine membrane to reduce dissolved minerals, metals, fluoride, PFAS, and many other contaminants.
S
T
- Total Coliforms (MPN/100mL)
- A broad group of bacteria used as a general indicator of water treatment effectiveness and distribution system integrity.
- Total Dissolved Solids (TDS) (mg/L)
- The total concentration of all dissolved minerals, salts, and organic matter in water.
- Trihalomethanes (THMs) (mg/L)
- Disinfection byproducts formed when chlorine reacts with natural organic matter in water.
- Turbidity (NTU)
- A measure of water clarity — how much suspended particles scatter light passing through water.