You can build water towers yourself. For this, there are standard albums for their construction. These standard solutions are more than 50 years old and they have proven themselves quite reliably.
If you really want to buy it, you can do it in any organization that is reliable in your opinion.
An article about water pressure Zen towers (what they are for and what they look like) - here.
I recommend that you write to them by mail - [email protected], they will tell you everything. And there you will find everything. So write, and everything will be done, they will throw you a site, and everything is on it.
We need private, clean and working)