Download of WatPro 4.0 was on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The most frequent installation filenames for the software are: javaw.exe, watpro.exe and Watpro2.exe etc.
We recommend checking the downloaded files with any free antivirus. This program is a product of Hydromantis. WatPro is suitable for 32-bit versions of Windows XP/Vista/7/8/10/11. The software lies within Photo & Graphics Tools, more precisely 3D Design. The most popular versions among WatPro users are 4.0, 3.0 and 2.0.
From the developer:
WatPro is the premier water treatment simulator for predicting water quality based on specific treatment processes and chemical addition (e.g. alum, ferric chloride, NaOH, lime).
WatPro uses raw water quality parameters such as pH, TOC and SUVA, and design and operating characteristics of process tanks, to simulate plant operation.
You may want to check out more software, such as VFDS, progeCAD 2008 Smart! or VizUp, which might be similar to WatPro.