It looks like there used to be a pump against the wall that has been removed that has other outlets there, maybe connected to flush toilets. Would I n ...
when opening the valve the pressure is stronger than any other tap but when I attach the hose fitting it loses that pressure and and comes out slowly ...
As mentioned that is a gravity feed system and the suggestion is a pressure pump.
More specifically you need a Peripheral Water Pump like this one:
ht ...
Great advice from @AlanM52 there @cassius23.
If you are looking for a pump in-store then I'd suggest something along the lines of a Ozito 800W Const ...