# HydroSewer vs CorroScan

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.

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.

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.

## The numbers

| Metric | HydroSewer | CorroScan |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 3 weeks | **Every 2 days** |
| Size | 51 MB | 27 MB |
| Requires iOS | **15.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Transparent Blue Water LLC](https://appshunter.io/developer/1847968351) | [OFO Tech](https://appshunter.io/developer/1435806692) |

## What reviewers say

### HydroSewer

[App page](https://appshunter.io/ios/app/hydrosewer-drainage-network/id6754671899)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| HydroSewer Pro | $14.99 | one-time |


### CorroScan

[App page](https://appshunter.io/ios/app/corroscan/id6789752647)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| CorroScan Pro | $14.99 | per month |
| CorroScan Pro (Annual) | $149.00 | per year |


## Frequently asked 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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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*