Peak Wastewater Flow Calculator
Average and peak dry weather flow plus inflow, from population and daily contribution.
Inputs
Results
Total design flow
30.44L/s
Peak dry weather flow plus inflow allowance
Average dry weather flow7.23L/s
Peak dry weather flow28.94L/s
Inflow allowance1.50L/s
Peaking factor applied4.0
The peaking factor is applied to dry weather flow only. Inflow and infiltration are entered as a single constant allowance.
Calculation details
Engineering equations
ADWF = P · q / 86 400
PDWF = ADWF · PF
Q_design = PDWF + Q_inflow
Variables
- P
- Contributing population (persons)
- q
- Average daily wastewater contribution (L/person/day)
- PF
- Peaking factor applied to dry weather flow
- Q_inflow
- Additional inflow allowance (L/s)
- ADWF
- Average dry weather flow (L/s)
- PDWF
- Peak dry weather flow (L/s)
- Q_design
- Total design flow (L/s)
Assumptions
- The daily contribution is uniform across the contributing population.
- The peaking factor is applied to dry weather flow only.
- Inflow and infiltration are combined into a single constant allowance in L/s.
- Groundwater infiltration is included only if it is entered as part of the inflow allowance.
Worked example
P = 2 500, q = 250 L/person/day, PF = 4.0, inflow 1.5 L/s
ADWF = 2 500 × 250 / 86 400 = 7.23 L/s
PDWF = 7.23 × 4.0 = 28.9 L/s
Design flow = 28.9 + 1.5 = 30.4 L/s
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Results are preliminary engineering estimates based on the stated assumptions. Confirm inputs, assumptions and requirements against the applicable standards and authority requirements before use in design or construction.