Water Quality Parameters-TASTE & ODOR:

TASTE & ODOR:

The terms taste & odor are themselves definitive of this parameter. Because they are sensations of taste and smell are closely related often confused, a wide variety of tastes & odors may be attributed to water by consumers.

Sources: 

→) Many substances with which water comes into contact in nature or during human use may impart perceptible taste & odor. These   include minerals, metals, and salts from the soil, end products from biological reactions, and constituents of waste water.

→) Inorganic substances are more likely to produce tastes unaccompanied by odor.

→) Alkaline material imparts a bitter taste of water, while metallic salts may give a salty or bitter taste.

→) Organic material produces both taste and odor.

→) Biological decomposition of organic may also result in taste and odor producing liquids and gases in water. e.g. sulfur that imparts a rotten egg taste and odor.

Impacts: 

→) Consumers find taste & odor aesthetically for obvious reasons.

→) Because water is thought of as tasteless & odorless, the consumer associates taste and odor with contamination and may prefer to use a tasteless, odorless water that might actually pose more of a health threat. And odors produced by organic substances may pose more than a problem of simple aesthetics.

Measurement:

→) Quantitative tests that employ the human senses of taste and smell can be used for this propose. An example is the test for the threshold odor number (TON). The TON of that sample is then calculated, using this formula, TON = (A + B)/A, where A is the volume of odorous water (mL) and B is water required to produce a 200 mL mixture.

Table: threshold odor numbers corresponding to sample volume diluted to 200 mL

Sample volume (A) (mL)	TON
200	1.0
175	1.1
150	1.3
125	1.6
100	2.0
75	2.7
67	3.0
50	4.0
40	5.0
25	8.0
10	20.0

Use:

→) Although odors can be a problem with wastewater, the taste and odor parameter is only associated with the potable water.

→) EPA does not have a maximum standard for TON.

→) A maximum TON of 3 has been recommended by the public health service and serves as a guideline.

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