# Civil Engineering - Waste Water Engineering - Discussion

### Discussion :: Waste Water Engineering - Section 1 (Q.No.19)

19.

When drainage to sewage ratio is 20, the peak dry weather flow is

 [A]. 20% of the design discharge [B]. slightly less than 5% of the design discharge [C]. slightly more than 5% of the design discharge [D]. none of these.

Explanation:

No answer description available for this question.

 Shreya said: (Apr 21, 2017) Anyone explain it please.

 Souvik Kundu said: (Jan 15, 2018) Please explain it.

 Rajeshkumar J said: (Feb 19, 2018) DWF = total supply of water * % of supply contributing to sewage, so when the ratio of drainage to sewage is high (20), then % of supply will be less, so DWF will be less than the design discharge.

 Raj said: (Mar 1, 2018) Please explain it.

 Er Mugundan R said: (Jul 1, 2018) Explain it, please.

 Khushwant Rana said: (Nov 19, 2019) In dry weather only dry weather flow mean drainage flow will occur not the stormwater taken into account if drainage: sewage =1:20 then at dry flow only 1 unit will flow in a total of 21 unit mean % flow as compared to rainy season =1*100/21 = 4.76.

 Hdhjdje said: (Dec 18, 2019) @Rana, Nice explanation.

 Harsh Sharma said: (Dec 31, 2019) Qd/Qs = 20. Qd = 20 Is ---- (1). In rainy weather; Q = Qd+ Qs. from eq (1)- Q = 21 Qs ----- (2). In peak dry weather; Q= Qd + Qs (here Qd = 0 since no storm water). Hence, Q= Is ----- (3). From ek (2) & (3). Dry weather condition/ Rainy weather condition = (Qs/ 21Qs)*100 = 4.76... Therefore, the peak dry weather flow is slightly less than 5% of the design discharge.

 Irfhan said: (Dec 6, 2020) Thanks @Harsh.