Get a blind filter and with the machine cold, or heating element disconnected adjust the pump to 9 bar....If the expansion valve still allows any water to flow at 9 bar, then Either it's scaled and leaking because of that, or maladjusted. If you raise the brew pressure again to 11.5 bar and adjust the expansion valve to just stop the flow...if it stops, good, if it doesn't, check for limescale on the seating of the valve or descale. The problem with the fact that it's probably been flowing out for some time and it sounds like your using crap water, means there is a strong possibility the seating is gunked up a bit.

The valve should be set to open at 11.5 or 12 bar and the brew pressure set to 9 bar.

You should be able to figure out the fine detail....Oh and hard water is the root cause of 95% of espresso machine problems, so I'd do something about that.

 

Thanks very much, I'll give that a go and see where it gets me. I'd stopped short of just adjusting the pump pressure back to 9 as given it was working fine until recently, was worried that would just be covering up some underlying problem which as you say is likely due to the crappy water in my area but that makes sense as a first step to see if i can track down the culprit.

 

And yes, water quality is a massive issue in my area. I use filtered, but it's still really hard even after going through the Brita so just have to lump it and backflush regularly

 

And yes, water quality is a massive issue in my area. I use filtered, but it's still really hard even after going through the Brita so just have to lump it and backflush regularly

Or buy bottled water [emoji6]