Comparison

HydroSewer vs CorroScan

Price, ratings, monetisation and update history for both apps, side by side โ€” with what reviewers say about each.

Head to head
About

HydroSewer

Features
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HydroSewer is a professional stormwater and sewer network analysis tool powered by the EPA SWMM 5 engine. Build, analyze, and simulate drainage networks from your phone or tablet. KEY FEATURES - Import standard EPA SWMM input files (.inp) and simulate them with the EPA SWMM 5 engine on your device, with no account and no cloud - Junctions, outfalls, storage, conduits, pumps, weirs, orifices, and subcatchments on an interactive canvas - Step through results over time: depth at nodes, flow and velocity in conduits, and more - Edit node, link, and subcatchment properties; renaming or deleting an element updates the data that refers to it, and broken references in older projects can be repaired - Give a node its sewage flow (DWF), with an optional hourly pattern, and a direct inflow; before a run, the app flags flat pipes, unset manholes, or no inflow at all - New network, Save, and Save as in the menu; Demo Village, a sample network, to try it all MAP BACKGROUND (OPTIONAL) - Your network over Google Maps, map or satellite, with adjustable visibility - Find your area on the map: tap your town and HydroSewer proposes the coordinate system that fits, if it knows one - Or set UTM, or a Transverse Mercator grid in Advanced - A .inp that declares a supported EPSG code (Q_VAR_PROJECTION) lands in place with no setup - Local coordinates? Line the network up by tapping a node and its place on the map, a few times - You turn the map on. It needs a connection; without one, the network is shown without it LAY OUT A NETWORK IN THE FIELD Start a new network and tap Use my location: the map centers where you are and a dot shows your position as you walk. Add each manhole by tapping its place on the map; your location never places or moves one. A preliminary layout, not a survey. FIELD NOTES - Attach notes and photos to any manhole, outfall, or pipe: as-built discrepancies, observations, a "check this" for the office - Open or resolved; elements with open notes are highlighted, and one list gathers every open note - With location allowed, a note records where it was taken and how accurately, with Show on map - Saved in your project, never in the .inp file CORE FEATURES WITHOUT INTERNET Modeling, simulation, saving, and field notes work with no connection, wherever the signal doesn't reach. Apart from the store's purchase service, only the optional map background uses the internet, through Google Maps. PRIVACY Transparent Blue Water does not receive your data. When you turn on the optional map background, Google Maps receives the map area you view. Your GPS reading, if you allow it, is used on your device and never sent anywhere; a note's position stays in your project and its PDF until you share them. FREE, WITH NO SIZE CAP No cap on network size, field notes, or photos; the map background is free too. HydroSewer Pro is an optional one-time purchase that adds: - Export the network as a standard SWMM .inp file - Export node and link results to CSV, every time step - A PDF report of your field notes with your logo, model data per element, the photos, and map links to where notes were taken - Save a network's alignment on the map IMPORTANT HydroSewer is an independent engineering tool. Results are computed by the EPA SWMM 5 engine and must be reviewed and verified by a qualified, responsible engineer before any design, construction, permitting, or other professional use. HydroSewer does not certify or guarantee compliance with any code, standard, or regulation, and is provided "AS IS" without warranty of any kind. HydroSewer is not affiliated with, endorsed by, or sponsored by the U.S. Environmental Protection Agency (EPA). References to EPA and SWMM are used solely to identify the simulation engine. Map data and imagery: Google Maps.

About

CorroScan

Features
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Point. Detect. Measure. CorroScan finds corrosion with on-device AI and measures its true area with LiDAR โ€” geotagged, logged, and PDF-ready in seconds.CorroScan turns your iPhone into a corrosion inspection instrument. Point the camera at rusted steel: on-device AI outlines every corrosion patch live, and the LiDAR scanner measures its true surface area โ€” no reference markers, no tape measures, no guesswork. DETECT โ€” a corrosion-trained neural network segments patches in real time, with stable outlines that survive camera motion. Distance, angle and light guidance keep every capture reliable. MEASURE โ€” LiDAR depth fused with the camera yields genuine surface area (cmยฒ/mยฒ) and span for each patch, with a stated tolerance. Multiple patches are measured individually and in total. LOCATE โ€” every scan is geotagged with a site name, browsable on a map and in a searchable, filterable log. REPORT โ€” generate clean A4 PDF defect reports with photo, outlines, measurements, GPS and capture conditions โ€” ready to send from the field. FREE โ€” 100 scans with full detection and measurement. Everything stays on your iPhone. CORROSCAN PRO (auto-renewable subscription, monthly or annual) โ€” unlimited scans and PDF defect reports. 100% on-device: no account, no cloud, your data never leaves your iPhone. TEAMS โ€” inspection companies equip their crews with organization seats, adding cloud sync and a web dashboard managed by the company. REQUIRES a LiDAR-equipped iPhone (iPhone 12 Pro or later Pro models). No ads, no tracking, no third-party analytics. Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/ Privacy Policy: https://corroscan.ai/privacy.html

Screenshots

HydroSewer4 screens
CorroScan4 screens

Verdict

The call

The clearest difference is update cadence: CorroScan at every 2 days against HydroSewer's every 3 weeks. HydroSewer's advantage is device support (3 vs 1) and iOS requirement (15.0 vs 17.0). On price, ads and in-app purchases there is nothing between them.

Scored on Price ยท Rating ยท Positive reviews ยท Number of ratings ยท Update frequency ยท Ads ยท In-app purchases ยท Monetization ยท Best chart rank ยท Devices ยท Requires iOS

CostPrice ยท In-app purchases ยท Ads ยท Monetization

Both are free to download. HydroSewer sells 1 one-off in-app purchase and CorroScan sells 2 in-app purchases, starting at $14.99 per month. Whichever you choose, the download price is not the number that matters.

UpkeepUpdate frequency

HydroSewer ships an update every 3 weeks, CorroScan every 2 days. The most recent releases landed on October 29, 2026 and October 24, 2026 respectively.

Scorecard3 real differences ยท 3 level
HydroSewer versus CorroScan: the parameters behind the verdict, then further details
ParameterHydroSewerCorroScan
PriceFreeFree
Update frequencyEvery 3 weeksEvery 2 days โ€” better
AdsNoNo
In-app purchasesYesYes
DevicesiPhone, iPad, iPod โ€” betteriPhone
Requires iOS15.0 โ€” better17.0
Further details โ€” not scored
Size51 MB27 MB
Age rating4+4+
DeveloperTransparent Blue Water LLCOFO Tech

In-app purchases

1 purchases

HydroSewer

One-time1
  • HydroSewer Pro$14.99
2 purchases

CorroScan

Subscriptions2
  • CorroScan Pro$14.991 Month
  • CorroScan Pro (Annual)$149.001 Year

Questions

Is HydroSewer free?
HydroSewer is free to download, with in-app purchases available.
Is CorroScan free?
CorroScan is free to download, with in-app purchases available.
Do HydroSewer or CorroScan have ads?
Neither HydroSewer nor CorroScan shows ads.
Which is updated more often, HydroSewer or CorroScan?
HydroSewer ships an update every 3 weeks, and CorroScan every 2 days. Most recently, HydroSewer was updated on October 29, 2026 and CorroScan on October 24, 2026.

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