Hey guys I currently have 4 water treatment plants next to each other all maxed level but only connected in groups of 2 and won't connect a 3rd room this is also with a few others is this a bug?

Nope. Max 3 sections can connect.

Delete one of the rooms. Then build and level a single section .

ok thanks ill try that

As an added bonus, Upgrade one room to max, then create a second and upgrade it seperately.

Saves on caps.