Question

There are industry standards, which set guidelines and requirements for water quality sampling. List these standards and succinctly explain the importance of adhering to standards in water quality sampling practice.

Answer 1

Guidelines for water quality sampling

1. The location of sampling point should be such that the sample of water collected should be the representative sample of different water sources that would be used for domestic and industrial purpose.
2. There should be at least one sampling point at the outlet of each water treatment plant.
3. The sampling points should be distributed along the pipe distribution and it must also consider the population of the community and demand of water.
4. The number of sampling pipe along the pipe distribution will increase with increase in number of branches of pipes.
5. Minimum number of samples depends on the population of people served by that water source.

Population	Minimum number of samples
<5000	1
5000 - 100000	1 per 5000 population
< 100000	1 per 10000 population + 10 additional sample

6. The water sample collected should be tested in less than 6 hours and in no condition it should not exceed 24 hours.

Water Quality Standards

PARAMETERS	STANDARDS
Total Solids	Acceptable limit = 500 mg/l Cause for rejection limit = 2000 mg/l
Turbidity	Acceptable limit = 1 NTU Cause for rejection limit = 10 NTU
Colour	Acceptable limit = 5 TCU Cause for rejection limit = 25 TCU
Taste and Odour	Acceptable limit = 1 TON Cause for rejection limit = 3 TON
Alkalinity	Acceptable limit = 200 mg/l Cause for rejection limit = 600 mg/l
pH	6.5-8.5
Hardness	Acceptable limit = 200 mg/l Cause for rejection limit = 600 mg/l For boiler feed water hardness < 75 mg/l For domestic water supply = 75 – 115 mg/l
Chlorine content	Acceptable limit = 200 mg/l Cause for rejection limit = 600 mg/l
Free Ammonia	Acceptable limit = 0.15 mg/l
Organic Ammonia	Acceptable limit = 0.3 mg/l
Nitrite	Acceptable limit = 0 mg/l
Nitrate	Acceptable limit = 45 mg/l
Iron (Fe)	Acceptable limit = 0.1 mg/l Cause for rejection limit = 1 mg/l
Manganese (Mn)	Acceptable limit = 0.05 mg/l Cause for rejection limit = 0.5 mg/l
Most Probable Number (MPN)	< 1 no./100 ml

Importance of adhering to standards in water quality sampling practice

1. It represents the true water sample which is going to be used for industrial and domestic purpose.
2. It identifies the contamination present in water and thus prevents the water born disease
3. It helps to know whether the minerals which are essential for the body are present in water.
4. It ensures that water is safe and meets all the water standards and can be used for drinking and other purposes.