I converted my (tank-less) Epoca E1 to run on a Brita Ultramax tank. I sit the tank atop the E1 and run 1/2" poly pipe to the pump. I have not had a problem with pressure since I had the pump rebuilt when I first acquired the machine.

When I made the conversion, I was in the mindset for electrical work. When I took the machine off of line pressure, the pump was fed by a 3/8" water line. (Higher voltage can use thinner wire). When I put the tank on, and was relying on gravity feed to the pump, I used 1/2" line. (lower voltage needs more amps).

Probably a stupid analogy, but I didn't want my pump struggling to pull water through a coffee straw. (lol pun)

Update- I bought and installed a reverse osmosis system over the weekend and connected my espresso machine to the house water supply. The machine at idle sits with about 2.5 bars of pressure and when pulling shots the pump is SO much quieter now. Need more time with it but initially it seems the shots are consistently a little better now. I still would like to see more pre-infusion time than what I am getting so I need to try and get that adjusted somehow.

2.5 bar seems like a lot. My machine sits at 1 bar normally. Here is the water tank mod on my Epoca. You can clearly see that the inlet water pipe is MUCH larger than the stainless that the pressure line was connected with.

I still would like to see more pre-infusion time than what I am getting so I need to try and get that adjusted somehow.

Do a forum search for "delay on make" relay and do a Google search using the same term. The electrical connection to the pump motor is usually fitted with a quick disconnect . . . you just need to find some compatible fittings. An electronics supply house or possibly Radio Shack should have these.

The "delay on make" does just what it says - it delays the application of voltage to the pump by an adjustable time period.

2.5 bar seems like a lot.

I really don't know if there is an "ideal" pressure for the pump inlet but 2.5 bar (~36 psi) seems like a winner. Your 1.0 bar is fine also but I know that ~3.0 bar has been judged to be a good value for pre-infusion purposes.

kajer, can I ask you what type of hose and fittings are those, and any idea where can I buy them online?
Here in Thailand stuff like that is not easy to find.
Thanks.