My old townhouse in Germantown had an adjustment at the water meter on the pressure relief valve, I had a plumber adjust it to 70 PSI which he said was as high as was allowed. At my house where I live now in Linthicum Heights, MD the pressure guage on my TIII says 50 and I don't have a adjustment at the meter, I do alright and my DI lasts quite awhile since I get a TDS post membrane of 3.