GravityFlow — Gravity Water Supply Network Designer

| GravityFlow Network Designer

Legend

Measure

0.0 m

Tool: Select — 0 nodes · 0 pipes · 0 m © Abdullah Ameen

Select a node or pipe on the map to view and edit its properties, or choose a draw tool on the left to add a new source, break-pressure tank, junction or pipe.

Nodes 0

Label	Type	Elev (m)	Demand

Pipes 0

Label	L (m)	DN (mm)	Material

Map Display

Pipe Color By

Animate flow direction (blue = velocity OK, orange = outside target range)

Run Calculate to see hydraulic results here.

Bill of Quantities

Currency / Unit Label (optional)

Pipes

Description	Unit	Qty	Unit Price	Amount

Nodes / Structures

Description	Unit	Qty	Unit Price	Amount

Pumps

Description	Unit	Qty	Unit Price	Amount

Labor / Crew Rates

Generic reference unit rates in USD — edit to match local crew wages before using for costing.

Work Item	Unit	Qty	Unit Price	Amount

Grand Total: 0.00

Show longitudinal section to:

Pick an end node above (after calculating) to draw the ground & hydraulic grade line profile from its source.

Nodes

Source / BPT Junctions

Pipes by Diameter

Demand Defaults

Default LPCD (L/capita/day) Peak Factor (max hour)

Design Criteria

Min velocity (m/s) Max velocity (m/s) Min residual pressure (m) Max residual pressure (m) Tank storage factor (% of downstream avg. daily demand) Minimum pipe diameter (DN)

Defaults

Default Hazen-Williams C Default pipe material

About

GravityFlow models a branched (tree) gravity water supply network. A Source is any fixed-head boundary (intake reservoir or storage tank). A Break Pressure Tank is a mid-network structure that resets the hydraulic grade line to its own water level — use it to control static pressure on steep terrain (combined reservoir → gravity schemes). Junctions are demand points (tapstands / consumers).

Loops are not supported — every junction must have exactly one path back to a source. This matches how rural gravity schemes are actually built, and it's what makes flows solvable directly from demand instead of needing an iterative solver. If you accidentally connect two paths into a loop, Calculate will flag it and tell you which pipe to remove.

This network is designed using the Hazen-Williams headloss equation:
hf = 10.67 × L × Q^1.852 / (C^1.852 × D^4.87)
Velocity is then found from the continuity equation: V = Q / A

GravityFlow is a free, browser-based tool for designing and costing gravity-fed rural water supply networks — no installation, no server, no account required.

Developed by Abdullah Ameen · August 2026
Contact: abdullah.ameenn@gmail.com

Basemap

Map Style

Click anywhere on the map to see its elevation.

Labels

Show node labels on the map

New Project

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Step 1 — Source Feasibility

Source / Well Yield

Population Projection

Bill of Quantities