Build
Getting started
New to this tool? Turn on Worked example beside the page title to load a 40 ML/d conventional plant and see how it all fits together. Turning it off, or Clear all at the foot of this tab, gives you a blank chain again.
The tabs are numbered in the order you work through them: build the chain, check the levels, read the profile, compare the flow envelope, then report and save. Flow units and the reference library are in Settings; the calculation basis is in About this model.
The model works backwards from a set final discharge level. This is normally a treated water tank top water level (TWL), a reservoir level, or a receiving water level.
Once that anchor is set, add components to build up the whole treatment train — pipes, channels, weirs, baffles, filters, membranes, screens, pumps, the lot. Each card you add sits further upstream than the one below it.
Where there are multiple process trains you only need to work backwards through one. Components have a streams field so you can say "this card represents 1 of 4 filters" and the section flow scales accordingly.
Add as much detail as you can — pipe lengths, fitting counts, channel FFLs, weir crest levels — and the result gets more accurate. Each card carries a live diagnostic showing velocity, head loss, key levels, and any sanity warnings.
Discharge anchor
Component chain
Levels
Guide: using this tab
A row-by-row look at every component in the chain — the calculated water level at each one, alongside whatever reference levels you've set (weir crests, channel FFLs, filter floors, tank TWLs).
The number at the start of the chain is the water level your source would need to deliver to push the design flow through everything downstream. If your real source can't reach it, either the plant is losing too much head somewhere or you need a pump in the chain.
Profile summary
Profile
Guide: using this tab
A visual of the hydraulic grade line through the plant — water level at every component, from the source side on the left to the discharge on the right. Components are evenly spaced; only the order matters, not the distance between them.
A step down in the line means a pump or membrane suction is restoring head at that point. A step up means head is being consumed — friction in a pipe, a weir, a filter, a TMP drop, that sort of thing.
Hydraulic Grade Line
Envelope
Guide: using this tab
Every component is solved three times — once at minimum flow, once at average, once at maximum — and the results are compared.
That comparison is where the design decisions live. Different parts of a plant are governed by different flows: pipes and baffles by max, free-fall weirs and self-cleansing velocities by min, channels by either depending on what you're checking. Solving one flow at a time hides this.
The warnings below only exist across cases. A weir that runs free at average flow and drowns at maximum has changed its calculation basis without telling you — that's the kind of thing this tab is for.
Operating envelope
Cross-case checks
Governing case & set levels
What drives head loss at max flow
Report & Save
Guide: using this tab
Pick which of the other tabs (Build, Levels, Profile) you want included, then download as either a PDF or a CSV. The tab selection applies to both.
For PDF: your browser's print dialog opens — choose "Save as PDF" as the destination. To get a clean output with no URL/page-number bar, untick "Headers and footers" in the print dialog options.
Save state writes a JSON file containing every input and the current results. Reload it later (or share it with a colleague) and the plant is restored exactly.