Gas fitter here needing some experienced plumbers advice. A family member has had a new kitchen + bathroom fitted. The hot water coming from her gravity tank has a very poor flow rate now at all her taps, as does the cold mains, strangely. After checking the usual suspects - stopcock, water in tank etc I then attached a water pressure gauge to the cold mains pipe going to the kitchen sink and was getting 1.5 bar. Hot water was around 0.1 bar which is pretty normal I believe for each. Yet very poor flow rate coming thru the actual taps. I done the same checks in the bathroom sink + bath and same outcome. Toilet is filling fine and electric shower pressure is fine. Is this due to the “wrong” kind of taps fitted? The old taps were all individual full turn types. Now theyre all mixer tap 1/4 turns. The ones in the bathroom are the waterfall type. Could these new tap choices be designed for a different pressure or could the 1-4 turn type be wrong in some way? Any advice appreciated cheers.