Civil Engineering - Water Supply Engineering - Discussion


Biochemical Oxygen Demand (B.O.D.) of safe drinking water must be

[A]. nil
[B]. 5
[C]. 10
[D]. 15
[E]. 20

Answer: Option A


No answer description available for this question.

Nagmani Kumar said: (Sep 2, 2015)  
What is the B.O.D. value of safe drinking water?

Purusothaman said: (Sep 5, 2015)  
BOD is typically reported as 5 day BOD and ultimate BOD at 20 C and reported as milligrams of oxygen consumed per liter (mg O/L). BOD 5 is used by regulatory agencies for monitoring waste water treatment facilities and monitoring surface water quality.

BOD is the biochemical oxygen demand of the water and it is related to the concentration of the bacterial facilitated decompose organic material in the water. A sample with a 5 day BOD between 1 and 2 mg O/L indicates a very clean water, 3.0 to 5.0 mg O/L indicates a moderately clean water and > 5 mg O/L indicates a nearby pollution source.

BOD is a laboratory test that requires a oxygen sensing meter, incubator, nitrifying inhibitors, and a source of bacteria.

P S Thanveer said: (Feb 13, 2016)  
Bod indicate the presence of microorganisms in water. And in a drinking water the presence of microorganisms would lead to the rejection of the water. Therefore it is checked that the bod for drinking water must be zero.

Somnath said: (Jul 11, 2016)  
Thanks for providing the details.

Ashish said: (Oct 17, 2016)  
BOD is the amount of O2 required for decomposition of biodegradable organic matter present in the system.

Salman said: (Oct 7, 2018)  
Bacteria take 5 days to consume up to 70% to 80% of food which is it's favourite food. And for the remaining 20% to 30% it takes nearly 50 days just to survive on it as that 20% is not it's favourite food.

So we can't wait for so long and hence we consider 5 days as 70% of consumption by bacteria is enough for us.

Rizu said: (May 11, 2019)  
BOD5 in India is also because of 5 days working schedule and two days weekend off.

So, the reading is measured only for 5 days.

Dinaol Eshetu said: (Nov 14, 2020)  
Thanks all for the details.

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