Water organoleptic characteristics

1. Water organoleptic characteristics

2. Water for drinking purposes should be
theoretically, by definition
Colourless
Odourless
Tasteless

3. Nevertheless, it is not absolutely true in which
respects to the taste
Odour can be perceived, and
Colour can be acquired
So, the first statement is not true; is a lie

4. Taste
Taste is used to determine the acceptability of drinking
water from a judgement based on sensory
evaluation (panels)
Nerve endings in papillae (tongue nervous terminals)
located on the tongue and stimulated by
chemicals
Temperature has an influence on the taste
The taste test, organoleptic, has no particular scientific
value but attempts to determine the acceptability
of water

5. When natural water crosses soils and subsoil in its natural
hydrological cycle, can dissolve a lot of substances
and carry on suspended solids and microorganisms
Chemical substances, mainly salts, can generate different
tastes and even odours
It does not mean that water is not potable, and the type
and quantity of salts create a difference among
bottled water brands

6. There are water brands characterised by the taste
E.g. from volcanic origin with a light taste of sulphur
Taste can be modified by the presence of gas
(carbonic mainly)

7. Odour
It is assumed that odour in water is caused by
chemicals, natural processes of decomposition
of vegetable mater or microorganisms activity
The odour test, organoleptic, has no particular
scientific value but also attempts to determine
the acceptability of water (panels)
During the present century, electronic “noses” have
been developed

8. There are water brands characterised by the odour
E.g. from volcanic origin with a light odour of sulphur
In analysing the odour thresholds of various substances in
water, it can be stated that human abilities indicate
the presence of concentrations as low as less than 1
µg/L or as high as 20 mg/L

9. The Odour Threshold Test is a quantitative (within its
limits) test and its scope is to determine the
minimum quantity of a chemical that produces an
odour
It is accomplished by using dilution water and a number of
persons to make up the panel, in consideration that
olfactory capability varies not only from person to
person but also in a given person from day to day or
even hour to hour
More details in DeZuane: Handbook of drinking water quality; 2nd ed. VNR, 1996

10. Quantitative terms used to describe taste and odour
are often catalogued as
• Swampy
• Grassy
• Medicinal
• Septic
• Phenolic
• Musty
• Fishy
• Sweet
among other

11. Taste and odour can be defined by
• Panels
• Electronic nose
• Identifying molecules by analytical chemistry

12. Colour
Several chemicals or microorganisms can generate
colours or precipitations in waters
Chemicals: Fe (red), Mn (black), Humic acids (grey,
red), clay (reddish)…
Can be determined by spectrophotometry

13. Sediments / deposits
- Clay
- Microbiological by-products
- Precipitation of chemicals
- Dead algae
- …

14. Several waters considered as “medicinal” by the
legislation of specific EU countries can be
characterized by its organoleptic
characteristics