Hi! Sorry for ignoring you for a while, i'm sorry to say that due to the way that factorio launches changing tile properties in launched game is probably possible but far beyond my programing capabilities, and workarounds i can think of are probably junky and resource hungry.
The easiest thing i can propose to you is to go factorio mods folder
%appdata%\Factorio or C:\Users[user name]\AppData\Roaming\%appdata%\Factorio on windows
or ~/.factorio on linux
extract water-removes-more-pollution_24.10.21.zip so resulting folder with the same name is in the mods folder,
and change the name and/or version to anything, add a one at the end for example,
put same change in the info.json file inside so factorio can pick it up and use it,
and then in data.lua file change 13/1e5 to your preferred absorbtion rate
0,000025 is around current rate in base game
0,00013 is what 13/1e5 means and to what it is modified
so you can try changing it to middle 0,00007
and then launching factorio and selecting that new mod
Or if all of that scary you can ask me again and i will make you a custom one cause there is actually plenty of pitfalls and that might be simpler :3c