Challenge
Due to the challenges posed by climate change, a growing population and changes in patterns of land use, Kent’s local water systems are under significant pressure. In response Kent County Council in partnership with Cranfield University had developed a rainwater harvest calculator in the form of an Excel tool.
They needed this to be converted into a clear and easy to understand web application, to help farmers work out rainwater harvest potential for their farm.
Solution
Japeto, formerly known as Fintek Software, took on the task of creating a user-friendly rainwater harvesting calculator tailored to the needs of farmers. We utilised the existing Microsoft Excel tool, enhancing it with the necessary data sets and algorithms, and transformed it into a straightforward and visually appealing online platform. This web-based tool now seamlessly integrates into our website using an iframe.
The improved tool provides access to 30 years of historical rainfall data, making it easy for polytunnel fruit farmers to calculate their irrigation water needs from rainfall, eliminating the expense of external sources. By simply inputting their irrigation and polytunnel covering dates, the calculator generates accurate rainwater accumulation predictions for various scenarios, including wet, average, and dry years. Armed with this valuable information and an understanding of their crop’s irrigation requirements, farmers can make informed decisions to save on water costs.
Live Data
The tool’s purpose is to explore how different sizes of a rainwater harvesting system affects cost savings. In the Excel tool, this takes time: you enter a single size and look at how it would perform. There’s no way to directly compare different sizes. Our solution addressed this by providing tools for farmers to adjust the size of the calculator and see the results updating in real-time. The results page lets the user change the size with a simple slider, and the page changes to show how that size of rainwater harvesting system would perform.
Accessibility
Local governments are legally required to meet a certain standard of accessibility so that people with disabilities can use their online services (WCAG 2.1 AA standard).We built and tested the rainwater harvesting calculator to comply with this standard. This involved using manual and automated testing to identify issues with colour scheme and contrast, (for people with visual impairments), making sure text-based alternatives exist for all graphics and graphs, and ensuring the structure of the calculator worked with screen readers and other assistive technologies.We provided an accessibility report which could help KCC ensure they comply with accessibility rules.
Ease of Use
The original tool was powerful but could be somewhat confusing to set up and use: it needs the user to have Excel installed and the user needs to change their security settings to run the tool. The data entry is quite overwhelming and the tool has an in-depth user manual. Our web-based version removes these obstacles. It’s accessible from any browser, with clear guidance through tooltips and labels. We also helped KCC streamline the interface by moving less-used inputs into an optional “advanced” section, making the default experience clean and simple.
Understanding the Tool
Behind the scenes, the app replicates complex calculations from the original Excel spreadsheet, including factors like rainfall history, crop water needs, and sowing dates. We worked with KCC to understand the Excel model and how soft fruit farmers operate, and reverse engineered the Excel algorithm to reproduce it in the calculator. Extensive testing ensured results match the Excel version exactly—just with a far better user experience.
Results
Farmers in Kent now have a practical online tool to estimate how much rainwater they can collect and how it translates into potential cost savings. By simplifying access to reliable data, the calculator supports better planning, more efficient irrigation, and ultimately, more sustainable farming practices.