# WPI Exam Prep vs Wastewater Operator Test Prep

The clearest difference is update cadence: Wastewater Operator Test Prep at monthly against WPI Exam Prep's every 3 months. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

WPI Exam Prep ships an update every 3 months, Wastewater Operator Test Prep monthly. The most recent releases landed on October 25, 2026 and October 9, 2026 respectively.

## The numbers

| Metric | WPI Exam Prep | Wastewater Operator Test Prep |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/wastewater-operator-test-prep/id6761349297/reviews)** |
| Number of ratings | — | **1** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Monthly** |
| Monetization | — | Free |
| Size | 120 MB | 28 MB |
| Requires iOS | 16.4 | **15.1** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Memorang](https://appshunter.io/developer/1011440560) | [Mike Watson](https://appshunter.io/developer/1848411021) |

## What reviewers say

### WPI Exam Prep

[App page](https://appshunter.io/ios/app/wpi-exam-prep/id6754835308)

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

**In-app purchases:** none


### Wastewater Operator Test Prep

[App page](https://appshunter.io/ios/app/wastewater-operator-test-prep/id6761349297)

This professional calculator provides 16 essential wastewater treatment calculations for licensed operators, covering Class I through Class IV certification math. It displays formulas and substituted values for easy verification and works completely offline, making it ideal for field use.

**Highlights:** 16 essential wastewater calculations, Supports Class I-IV certification math, Shows formulas and substituted values, Works 100% offline, Large, readable results for field use, Copy result for sharing, Calculation history

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

**In-app purchases:** none


## Frequently asked questions

### Is WPI Exam Prep free?

WPI Exam Prep is free to download, with no in-app purchases.

### Is Wastewater Operator Test Prep free?

Wastewater Operator Test Prep is free to download, with no in-app purchases.

### Do WPI Exam Prep or Wastewater Operator Test Prep have ads?

Neither WPI Exam Prep nor Wastewater Operator Test Prep shows ads.

### Which is updated more often, WPI Exam Prep or Wastewater Operator Test Prep?

WPI Exam Prep ships an update every 3 months, and Wastewater Operator Test Prep monthly. Most recently, WPI Exam Prep was updated on October 25, 2026 and Wastewater Operator Test Prep on October 9, 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.*