# Rain Harvest

> Simple calculator for estimating rainwater runoff from surfaces. (iPhone/iPad app by Mark Smith.)

- Source: https://appshunter.io/ios/app/rain-harvest/id322055663 (this page in markdown: same URL + `.md`)
- Developer: [Mark Smith](https://appshunter.io/developer/322055666)
- Category: Reference, Weather
- Price: Free
- Rating: 4.00/5 from 1 App Store ratings · 4 written reviews indexed
- Age rating: 4+
- Requires: iOS 12.0 · 1 MB
- Languages: English
- Released: 2009-07-13
- Data updated: 2026-06-10
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/rain-harvest/id322055663/reviews.md

## What is Rain Harvest?

Have you ever wondered how much rain falls on your roof during a typical rain storm? Use this simple rain harvesting calculator to find out. You will be amazed at how much water can be collected from your roof (or any other surface) during even the shortest of rain storms. Why not collect and store this wonderful natural resource and put it to good use later to water your organic garden? 

A simple calculator interface allows for the input of:

Catchment surface area in square feet or square meters
Rainfall in inches or millimeters
Surface efficiency as a percentage 
Number of collection points

The final result is then presented in total gallons or liters of collected runoff. Gallons or liters per collection point is also calculated when more than one collection point is entered into the calculator.

Happy Rain Harvesting!

## Key features

- Rainwater collection calculator
- Input surface area (sq ft/m)
- Input rainfall (inches/mm)
- Surface efficiency percentage
- Calculate total runoff (gallons/liters)
- Runoff per collection point

## Recent user reviews (4 of 4)

All indexed reviews: https://appshunter.io/ios/app/rain-harvest/id322055663/reviews.md

### 1/5 — Don't like it

*2012-07-06, version 3.0*

Don't understand it.

**Developer response:** It's a free a calculator... Understand?

### 5/5 — Fast & Simplistic

*2011-04-22, version 2.0*

This is a great app for giving you an idea for collecting rainwater!

### 4/5 — Great for contractors

*2009-10-10, version 0*

Easy to use for quick information on potential system size and design.

### 4/5 — As promised

*2009-09-20, version 0*

Does exactly what it says it does. Simple & effective.

## Frequently asked questions about Rain Harvest

### How does Rain Harvest calculate collected water?

Rain Harvest uses your input for catchment surface area, rainfall amount, and surface efficiency to calculate the total volume of collected runoff. It can also provide a per-collection point estimate if multiple points are specified.

### What units can I use with Rain Harvest?

You can input catchment surface area in square feet or square meters, and rainfall in inches or millimeters. The results are presented in total gallons or liters of collected runoff.

### Is Rain Harvest suitable for calculating water from different surfaces?

Yes, the app is designed to calculate water collected from your roof or any other surface by allowing you to input the specific catchment surface area.

### Does Rain Harvest have ads?

No, Rain Harvest is ad-free, providing an uninterrupted experience for its users.

### What devices does Rain Harvest support?

Rain Harvest is available on iPhone, iPad, and iPod devices.

### How often is Rain Harvest updated?

The latest version, 5.0, was released on December 6, 2019. While not updated frequently, it remains a functional tool for its intended purpose.

### What is the age rating for Rain Harvest?

Rain Harvest has an age rating of 4+, making it suitable for a wide range of users.

### Can Rain Harvest help me plan for gardening?

By estimating the amount of water you can collect, Rain Harvest can help you plan for watering your organic garden, especially during dry periods.

## Version history (last 5 releases)

### 5.0 — 2019-12-06

Updated for iOS 13

### 4.0 — 2014-11-01

Completely new user interface for iOS 8.
You can now save, add, edit and search multiple calculations.
Email and print your calculations.

### 3.0 — 2012-04-08

✓ Share your calculations via email. 
✓ Print calculations from the device (requires an AirPrint compatible printer). 
✓ Universal app is now iPod, iPhone and iPad compatible. 
✓ Minor bug fixes and user interface enhancements.

### 2.0 — 2010-06-13

Version 2.0 now supports:

1) Both US and Metric calculations.
2) The ability to save user preferences.

### 1.0 — 2009-07-13

No release notes.

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## More apps by Mark Smith

- [ezReceipt](https://appshunter.io/ios/app/ezreceipt/id398453602)

All apps by Mark Smith: https://appshunter.io/developer/322055666

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-10.*