AI-powered
plumbing design

Pipe sizing is still done by hand

Identify every fixture. Assign fixture units. Sum loads along every branch and riser. Convert to flow rates. Check pressure at the worst-case fixture. Size every pipe segment against code tables. For a 3-storey residential building, this takes 8–16 hours of an engineer's time — and every design revision means doing it again.

It's not that better methods don't exist — it's that the industry's workflow never modernized around them. An industry survey of plumbing designers found that 43% still size systems using Hunter's Curve or a derivation of it — a probability model developed in 1940 — while another 35% use IPC/UPC code tables built on the same foundation, and 12% rely on self-developed methods based on personal experience.¹ Only 10% had adopted IAPMO's modern Water Demand Calculator. The dominant "tools" behind all of these methods? Hand calculations and spreadsheets, rebuilt from scratch, project after project.

Manual handoffs are burning real money

Sizing is only the start. Equipment selection, fixture schedules, motor lists, and specifications are still compiled by hand — from manufacturer catalogues, distributor phone calls, and copy-paste between disconnected files. Every manual handoff is a chance for an error to slip through, and errors that slip through design surface on site, where they're most expensive to fix.

The industry has quantified this. A landmark 2018 PlanGrid/FMI study of nearly 600 construction leaders found that time spent on non-optimal activities — fixing mistakes, hunting for project data, resolving conflicts — costs US$177.5 billion per year in labour in the U.S. alone, with rework caused by miscommunication and bad or inaccessible data accounting for US$31.3 billion annually.² The same study found each project team member loses more than 14 hours every week to these avoidable issues. And the design side owns a large share of the root cause: rework consumes roughly 5% of total project cost on average,³ with design errors and omissions accounting for approximately 28% of rework cost — second only to owner-driven changes.⁴

Oversizing is the industry default

When the sizing method is 80 years old and every recalculation costs hours, designers do the rational thing: size conservatively and move on. The result is systematically oversized pipes, pumps, water heaters, and booster systems on project after project — capital cost that nobody sees, because it's buried in "how it's always been done."

Hunter's Curve was built in 1940 around high-flow fixtures and congested-use assumptions that no longer reflect real buildings — and studies have confirmed it consistently over-predicts demand in most building types.⁵ IAPMO's modern, statistically derived Water Demand Calculator produces up to 65% lower peak demand estimates for single-family and multi-family buildings, translating to a 1-to-3 pipe-size reduction on service lines.⁶ An independent Arup analysis went further: sizing with the WDC instead of Hunter's Curve cut operational carbon by 73–84% in high-rise booster-pump applications, with embodied carbon savings of 20–41% and water savings up to 71,000 gallons annually per building.⁷ Oversizing isn't conservative — it wastes capital and energy, and oversized pipes increase water age and stagnation risk in the system.⁵

This is exactly the kind of value engineering that gets missed when sizing, pricing, and procurement never talk to each other. MEP Assist™ supports both NPC 2020 and the IAPMO Water Demand Calculator — recognized in the City of Vancouver Plumbing By-law since 2023 — so right-sizing is one click, not a research project.

The tools were never built for this workflow

A plumbing designer's workflow spans three worlds — calculation, drawing, and procurement — and today, three disconnected tool categories serve them. None of them talk to each other, and none of them was actually built for hydraulic design.

Calculation tools barely exist as products: the survey data above shows the real "market leaders" are spreadsheets and hand calcs.¹ Even IAPMO's own Water Demand Calculator ships as a free Excel workbook and phone app⁸ — a calculation aid, not a design environment. Results still get transferred to drawings by hand.

CAD and BIM platforms sit at the other extreme. Revit runs roughly US$3,000 per seat, per year⁹ — before training, hardware, and add-ons like MagiCAD priced on top — and it's fundamentally a modelling and documentation environment: powerful for coordination, but its MEP hydraulic sizing is not the reason firms buy it, and smaller plumbing-focused practices often can't justify the cost or learning curve at all. So the industry splits the work: calculate in a spreadsheet, draw in CAD, and manually keep the two in sync through every revision.

Procurement is the third island. Once systems are sized, engineers select pumps, heaters, valves, and expansion tanks by searching manufacturer catalogues and phoning distributors for pricing — then compile equipment schedules by hand. No tool connects calculated duty points to real, purchasable products.

MEP Assist™ was built to be the missing connection: calculation, drawing output, and equipment data in one flow — and you keep the CAD software you already rely on, because designs export to PDF, DXF and DWG.