Project Information
Section 1: Development Profile
BS EN 752 defines population equivalent (PE) based on residential occupancy. Enter dwelling numbers or specify total population. Commercial loads add employees and visitor flows.
Residential Dwellings (per capita: 150 L/person/day)
Commercial Loads
Commercial foul load is approximated as a population equivalent (employees + visitors ÷ 10) and carried through the same conservative per-capita DWF. This is a screening estimate: for detailed commercial or industrial foul design, use the appliance discharge-unit method of BS EN 12056-2, or a metered per-employee allowance where available.
Peak Factor Selection
BS EN 752:2017 defines peak factors based on population equivalent: 6.0 × DWF for PE < 100, reducing to 4.0 × for PE > 1000. You can override with a custom peak factor.
Section 2: Flow Calculation
Dry Weather Flow (DWF) = PE × per capita consumption (L/person/day) / 86400 (L/s)
Peak foul flow = DWF × peak factor
Design flow includes infiltration allowance and trade waste. The 150 L/head/day default is a conservative domestic dry-weather-flow basis (adoptable-DWF lineage) — commercial and mixed developments are estimated here via population equivalent; for detailed commercial design, size to the appliance discharge units of BS EN 12056-2.
Catchment Area (for infiltration)
Results
Total PE
0
persons equivalent
Dry Weather Flow
0.00
L/s
Peak Foul Flow
0.00
L/s
Design Flow
0.00
L/s
Section 3: Pipe Sizing
Colebrook-White transitional law (foul roughness k_s = 1.5 mm, Water UK DCG). Foul pipes are designed to run no more than 3/4 full at peak, with self-cleansing velocity >= 0.75 m/s at 1/3 pipe full (BS EN 752 / Water UK DCG) to prevent deposition.
Pipe Properties
Gradient & Velocity
Compliance Check
| Parameter | Value | Status |
|---|---|---|
| Design Flow (L/s) | 0.00 | |
| Pipe Capacity @ 3/4 Full (L/s) | 0.00 | |
| Velocity @ 1/3 Full (m/s) | 0.00 | |
| Gradient (1 in X) vs minimum | — | |
| Minimum diameter (by basis) | — |
Section 4: Combined System Check (Optional)
For combined systems, combined flow must not exceed 6 × DWF + infiltration + 2 × DWF for dilution. Surface water drainage must meet drainage design requirements separately.
Combined System Results
Surface Water Flow
0.00
L/s
Combined Flow
0.00
L/s
Limit (6×DWF + inf. + 2×DWF)
0.00
L/s