HB wrote:Since the filters introduce drag, the pressure regulator should be after them. The final order: mains > softener filter > carbon filter > pressure regular > accumulator > espresso machine.

Sorry if I'm hijacking this thread but you have me concerned. I have a pressure regulating valve attached to the main incoming water supply that I have adjusted to 3 bar for my Faema Legend (the pressure gauge on the machine reads 2.5 bar). Attached to the outgoing side of the regulator is a 3/8 hose which is connected to a Claris water filter. Attached to the outgoing side of the Claris is another 3/8 hose which leads straight into the machine. Correct me if this is the wrong way.

The reason you put the regulator after all of the filters is because the filters will reduce the line pressure. If you put your regulator before the filters, then set the regulator pressure to say, 4 bar on the regulator pressure gauge, the pressure reaching your machine may be 1 bar due to the flow restriction of the filters. Now if you adjust your regulator pressure using the pressure gauge on the machine and not a gauge on the regulator, it is not much of an issue. You are reading the actual mains pressure at the machine. I would run mans>1/4 turn shutoff valve>filter system>1/4 turn shutoff valve>regulator>machine. That way you can isolate the filter system for maintenance and shut off the water if you will be away for an extended period of time (vacation).