Sewer Design Standards & Guidelines
The basic Sewer Design Standards and Guidelines are designed for two different types of sewers, sanitary and storm.

Sanitary Drainage Design Criteria:
Size: Sanitary sewer mains shall be of adequate size to convey population generated (peak dry weather) flows, plus a general allowance for inflow and infiltration, plus an allowance for inflow allowance for manholes in sag locations. The inside diameter of sanitary sewer pipes must measure at least 200 mm.
Population Generated Flows: Residential population generated flows are determined by the following formula:

Qpdw = G x P x PF/86,400

where:


MINIMUM SANITARY SEWER SLOPE TABLE

DN dia mm
V=0.80 m/sec
V= 0.73 m/sec
150
0.0063
0.63%
0.0056
0.56%
200
0.0044
0.44%
0.0039
0.39%
250
0.0033
0.33%
0.0029
0.29%
300
0.0026
0.26%
0.0023
0.23%
350
0.0021
0.21%
0.0019
0.19%
400
0.0018
0.18%
0.0016
0.16%
450
0.0016
0.16%
0.0014
0.14%
500
0.0014
0.14%
0.0012
0.12%
600
0.00109
0.109%
0.00096
0.096%
700
0.0009
0.090%
0.0008
0.080%
800
0.00077
0.077%
0.00068
0.068%
1000
0.00058
0.058%
0.00051
0.051%
1200
0.00047
0.047%
0.00041
0.041%
1400
0.00039
0.039%
0.00034
0.034%
1600
0.00033
0.033%
0.00029
0.029%
1800
0.00028
0.028%
0.00025
0.025%
2000
0.00025
0.025%
0.00022
0.022%
2400
0.0002
0.020%
0.00018
0.018%
Free Online Manning Pipe Flow Calculator  pipe flow calculator at hawsedc.com.
minimum gravity line slope