
Sewer Pipe Calculator
Manning Gravity Pipe Design
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About
Sewer Pipe Calculator designs and checks gravity sewer and storm drain pipes with the Manning equation for partially full circular pipes. Enter what you know and get what is missing.
6 GRAVITY CALCULATORS (FREE)
• Velocity & Depth: flow, slope and diameter → velocity and water depth
• Diameter from Flow: minimum diameter and the next commercial size from your catalog
• Slope Range: minimum and maximum slope that meet velocity, depth and self-cleansing criteria
• Minimum Slope & Diameter: when only the flow is known
• Flow & Velocity from Depth: analyze an existing pipe
• Flow Analysis: flow, velocity, hydraulic radius, h/D, Froude number and tractive force
SELF-CLEANSING CHECK
Tractive force τ = ρ·g·R·S next to the velocity, with a color verdict: self-cleansing OK or sedimentation risk. A pipe can meet the minimum velocity and still fail on tractive force.
PIPE CATALOGS
PVC, concrete, vitrified clay and corrugated HDPE (SI and US) with their Manning n and commercial diameters.
PRO
• Export any calculation to PDF and save/load calculations
• Custom pipe catalogs
STRUCTURES PACK
Inverted siphon (automatic sizing), pump station (wet well volume, pump power, cycle times), weirs and overflows, minor losses and manholes, orifices and gates.
FORCE MAIN PACK
Total dynamic head with Hazen-Williams, economic diameter (Bresse) and water hammer (Joukowsky), with the TDH passed straight to the pump station.
COLLECTOR DESIGNER
Design a full sewer line segment by segment, like a spreadsheet: flow accumulates and invert levels propagate downstream, every segment is checked for velocity, tractive force, h/D, cover and surcharge, with a longitudinal profile and a PDF design table.
SI and US units. English and Spanish. Works offline.
For civil and sanitary engineers, designers and students working on sewer networks, storm drainage and simplified sewerage systems.
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What's New in Sewer Pipe Calculator
1.0.10
October 11, 2026
Performance improvements and minor fixes.
3
Subscriptions & In-App Purchases
$7.99
Sewer Designer
Design gravity sewer lines segment by segment











