Gravity Sewer Capacity Calculator
Design capacity of a gravity sewer at the standard d/D = 0.8 fill ratio.
Sewers are designed to run 80% full at peak — the air space controls septicity and surcharge. Capacity at 0.8 fill is ~98% of full-bore.
Formula
Gravity Sewer Capacity Calculator is a free sewer capacity for process, mechanical and water engineers — instant, accurate and 100% client-side, with the governing formula and reference shown next to the result so the number can be defended, not just quoted.
About Gravity Sewer Capacity Calculator
Design capacity of a gravity sewer at the standard d/D = 0.8 fill ratio. The calculation implements Q_full = (1/n)·A·(D/4)^⅔·√S; Q(d/D=0.8) ≈ 0.98·Q_full (CPHEEO Manual on Sewerage / ASCE MOP 60). Sewers are designed to run 80% full at peak — the air space controls septicity and surcharge. Capacity at 0.8 fill is ~98% of full-bore.
How to use Gravity Sewer Capacity Calculator
- 1Enter Sewer diameter in mm.
- 2Enter Slope.
- 3Enter Manning n.
- 4Read Capacity at d/D = 0.8, Full-bore capacity, Full-bore velocity instantly — no submit button needed.
- 5Need US units? Flip the SI/Imperial toggle and every field converts.
Why use Gravity Sewer Capacity Calculator?
- ✓Implements the standard formula — Q_full = (1/n)·A·(D/4)^⅔·√S; Q(d/D=0.8) ≈ 0.98·Q_full
- ✓Reference cited on-page: CPHEEO Manual on Sewerage / ASCE MOP 60
- ✓One-click SI ⇄ Imperial toggle — values convert in place, physics stays in SI
- ✓Runs entirely in your browser — nothing uploaded, free forever
Frequently asked questions
What formula does the Gravity Sewer Capacity Calculator use?+
It computes Q_full = (1/n)·A·(D/4)^⅔·√S; Q(d/D=0.8) ≈ 0.98·Q_full, per CPHEEO Manual on Sewerage / ASCE MOP 60. The formula is displayed under the result.
What should I keep in mind when using this calculator?+
Sewers are designed to run 80% full at peak — the air space controls septicity and surcharge. Capacity at 0.8 fill is ~98% of full-bore.
Does this work for any fluid?+
Yes — density and viscosity are inputs (with common fluids suggested in the field hints), so the same physics applies to water, oils, gases and process fluids. Compute always runs in SI internally, so unit mix-ups can't corrupt the result.
Is the Gravity Sewer Capacity Calculator free to use?+
Yes — completely free, no sign-up, no limits. It runs client-side in your browser, so inputs stay private and results are instant even on slow connections.
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