The update adds 3 universal water tanks, Fire Tank addon, Water Tank trailer and Heavy Water Tank Semitrailer. They all are lazy retextured variations of fuel tanks (and to be honest, only Water Tank Trailer looks good). But if it'd be possible, could the models be modified to add a little of pipework and maybe some generic water hose like it is present on other water tanks (that are not used in-game as watertanks)?

Also, the water tank is missing from Paystar Twinsteer, ZiKZ 605R and DAN 96320 because all they have custom variants of normal fuel tanks, it's an easy fix, likely no textures alterations (well, maybe for Paystar). Look into it too.

Second of all, CAT 745C has a modelled, unique, custom made water tank in game files, sitting there for 3 years doing nothing, it takes less than a minute to make it an usable implemention to carry water at last just like you guys did with Log Carrier in Season 3!
C'mon, it takes nothing to have something cool, no lazy retexturing.

But, the game has two more vehicles that in vanilla game come with water tanks, however those water tanks are used as fuel ones, those are being Loadstar 1700 (used as a real life fire truck) and CAT 770G, it'd be shame if those hadn't their tanks properly used, even if you'd had to make yet another lazy retexture like I did.
Tatra Phoenix could use one too, especially since you guys have an early unused model of fuel tank (which is not a fuel tank irl either) dated back before August 2021, which could be reused and retextured

And lastly, since you've already reused all the base game fuel tanks, retextured as water ones, do the scout trailer too...