6.2.1 An overview of physical characteristics

The appearance, taste, odour, and ‘feel’ of water determine what people experience when they drink or use water and how they rate its quality; other physical characteristics can suggest whether corrosion and encrustation are likely to be significant problems in pipes or fittings. The measurable characteristics that determine these largely subjective qualities are:

• true colour (the colour that remains after any suspended particles have been removed);

• turbidity (the cloudiness caused by fine suspended matter in the water);

• hardness (the reduced ability to get a lather using soap);

• total dissolved solids (TDS);

• pH;

• temperature;

• taste and odour;

• dissolved oxygen.

Colour and turbidity influence the appearance of water. Taste can be influenced by temperature, TDS, and pH. The ‘feel’ of water can be affected by pH, temperature, and hardness. Rates of corrosion and encrustation (scale build-up) of pipes and fittings are affected by pH, temperature, hardness, TDS and dissolved oxygen.

Each of the physical characteristics is discussed separately in the fact sheets in Part V. However, there is some overlap with organic compounds, microorganisms and, most notably, the inorganic constituents of water; when this occurs, it is noted and cross-referenced.