Four calculation engines — Sedimentology, Water Quality, Hydrology & Hydraulics, Conveyance — with live USDA soil data, NOAA rainfall, and physics-based BMP routing. In a browser.
14 days free. No credit card. Engines validated against published worked examples — see the deltas.
The tools work. But the way they work hasn't kept up with how engineers actually build projects today. And the price hasn't gotten any more reasonable — perpetual licenses still run $3,000 to $8,000 per seat, locked to a single machine.
Legacy tools are Windows executables. No collaboration, no browser, no mobile. License tied to one machine. Need to open the model from another office, or hand it to a reviewer? Too bad.
You get a number. You can't see the formula, the substitution, or the intermediate steps. Review takes longer than it should because you're reverse-engineering output instead of reading it.
Hydrology in one app, sediment in another, water quality in a third. Copy-paste between them. Re-key inputs. Hope nothing drifts between analyses that should share the same watershed data.
Hand-reproducible stormwater calcs with every formula shown — the same methods as our free PE-Calc tools, extended into full design workflows.
5-acre residential subdivision — CN, Ia, Q, and volume step-by-step (matches TR-55).
Modified Puls routing to pre-development peak on a 10-acre commercial site.
48-inch CMP crossing — which control governs headwater, and how to fix it.
Rational method, time of concentration, Manning's, bioretention, sediment, and more.
HydroComplete models your entire site as a connected system. Watershed properties feed into BMPs, BMPs chain together, and pollutant removal compounds through the train — all in one project, with one set of inputs.
USDA SSURGO soil properties, NOAA Atlas-14 rainfall depths, NLCD land cover, and 3DEP elevation — all from one map click. No more toggling between Web Soil Survey, PFDS, and the NLCD viewer.
Stokes/Rubey settling velocity for each particle bin. Camp-Hazen basin trap efficiency. Darcy's law through bioretention media. Kadlec k-C* wetland kinetics. Real equations, not interpolated charts.
KaTeX-rendered formula steps for every result: the equation, the substitution with your inputs, the computed value, and the published reference. If a reviewer asks where a number came from, point at the screen.
Modified Puls detention routing, auto-sized orifice, pre/post comparison table. Build both conditions in the same project and generate the comparison deliverable without switching tools.
Each engine implements the published, peer-reviewed equations directly. No wrappers around someone else's code. No lookup-table interpolation pretending to be physics.
How it's different: resolves particle-size distribution across 7 bins instead of treating sediment as a single bulk value. Every settling calculation uses actual grain diameters.
How it's different: chains BMPs into a treatment train with compounding removal, not isolated percent-removal assumptions. Pollutant concentrations propagate through each stage.
How it's different: pre-dev and post-dev share one project with linked watershed data. Change a CN and both hydrographs update — no re-keying between files.
How it's different: solves normal and critical depth iteratively instead of requiring you to guess-and-check. 14 cross-section shapes, not just circular and trapezoidal.
The same worked examples a reviewer would reach for, run through the shipped engines on every deploy. Reference value, our value, the delta.
18 published cases, 53 checks: 52 within the source document’s own precision. The one that isn’t is explained on the page, not hidden behind a tolerance. See every case, every formula, every delta →
The HydroCAD and HEC-HMS numbers come from a real project file imported through the .hcp and .basin importers and run side by side with the vendor's own printed report, anonymized. Send us yours and we'll publish the delta with your permission.
Real-time data pulls from four federal agencies. Draw a site boundary and get soil properties, design rainfall, land cover, and elevation in one request. No more toggling between government websites.
This replaces the manual SSURGO/NOAA lookup workflow that typically takes 30+ minutes per site — navigating Web Soil Survey, downloading PFDS tables, cross-referencing NLCD pixels. One click, four federal datasets, done.
Core hydrology and hydraulics stay free and formula-transparent. Pro tiers add provenance export, sealable reports, and team seats for regulated work.
30-day pilot for dam safety teams updating EAP figures. Pairs with PE-Calc Field AR and open swmm-breach hydrographs.
Try FieldHydro demoNever gates fundamentals: SCS, Rational, Manning, and routing math run in the open calc engine. Subscribe for regulatory-ready deliverables.
Start free trialhydro-tools CLI + librarySame reference test vectors across languages (e.g. trap flow ~17.656 cfs, HGL step ~0.500 ft). Audit any step by hand.
PE-Calc free toolsQuestions on pilots or agency workflows: support@hydrocomplete.com
No black boxes. Every result traces back to a published method you can check by hand.
The methods, worked examples, and compliance logic are written and reviewed by a licensed Professional Engineer — not generated from a spec sheet.
SCS/TR-55, Rational Method, Manning, HGL/EGL, and RUSLE follow FHWA, NRCS, and USACE references — cited on every worked example.
The calc engine is open and mirrored in Python, JavaScript, and Rust against shared test vectors. Verify any step yourself — the fundamentals are never gated.
A growing library of fully-solved NC/SC examples with every formula and number shown — the same math the app runs. Browse the examples.
14-day free trial on every plan. No credit card required to start. The trial is fully functional — all four engines, unlimited projects, real PDF reports. Not a limited demo with features locked behind a paywall.
14 days free, no credit card
14 days free, no credit card
14 days free, no credit card
Honest answers. No marketing spin.
Short version: HydroCAD does your pond. HydroComplete does everything else on the stormwater permit — sediment basin sizing, RUSLE/MUSLE soil loss, water-quality volume and pollutant removal, treatment trains across BMPs, conveyance and HGL, and the NC MDC compliance checklist — in one project, in a browser, with every formula shown.
On routing specifically: the Hydrology engine implements SCS unit hydrographs, Modified Puls reservoir routing, compound outlets (orifice, weir, riser, V-notch, culvert), tailwater-coupled multi-pond backwater, and outlet auto-sizing, and it is checked against published worked examples on the validation page. On a real 55-acre HydroCAD project imported through the .hcp importer, HydroComplete reproduces HydroCAD's 100-year peak inflow to the pond exactly (410.34 vs 410.34 cfs), the 2-year peak within 0.3%, the culvert outlet flows within 0.4%, and the 2-year pond stage to the hundredth of a foot; the one place the two tools diverge is above the top of the stage-storage table, where HydroCAD holds storage constant and we extend the top area, and both tools warn. HydroCAD has thirty years of refinement on that workflow; we don't claim to have matched every corner of it yet. If you already have the pond in HydroCAD, import the .hcp and keep going here.
Yes. Project → Import accepts HydroCAD .hcp, HEC-HMS .basin, and EPA SWMM .inp files. Subcatchments, ponds with stage-storage and outlet devices, reaches, and the routing links between them come across as nodes on the diagram, keeping the original node numbers so you can cross-reference your existing report. Anything the importer can't map (custom rating tables, device types we don't model) is listed as a warning so you know exactly what to re-enter, rather than silently dropped.
The engines use published, peer-reviewed equations: RUSLE from USDA ARS, MUSLE from Williams (1975), SCS Unit Hydrograph from NRCS TR-55, Modified Puls routing from USACE / HEC-22, Manning's equation from Chow (1959).
Every result is shown with its formula, the substitution using your inputs, and the computed value — so you (or your reviewer) can verify each step by hand if you want to.
The Sedimentology engine implements the same RUSLE / MUSLE soil loss methods and the same trap efficiency calculations as legacy sediment tools. The Water Quality engine implements 15 BMP types with water-quality-volume sizing and buildup / washoff pollutant loading.
Honest answer: the original desktop apps are still authoritative for some specialized workflows, and we don't pretend otherwise. HydroComplete is designed to cover the core day-to-day use cases with better transparency, better integration across engines, and a modern interface.
Trial reports are watermarked "TRIAL - NOT FOR REGULATORY SUBMITTAL" on every page. Subscriber reports are clean and include the engineer-of-record information you enter in project settings. Applying the PE seal is the user's responsibility under the rules of the state where the work is performed — HydroComplete generates the deliverable, you stamp it.
The editor loads in your browser, but calculations run on our server through an authenticated API so the engines stay consistent across users and versions. There is no offline mode right now. You need an internet connection to compute.
Through the Stripe customer portal, any time, in about three clicks. There is no contract, no cancellation fee, and no "call us to cancel" routine.