A pump will boost the pressure, but it still needs the volume to push. If it can't suck the volume of water through the pipe from the mains, then the volume and pressure it will supply to the house will be limited. This can lead to cavitation in the pump which will damage it in the long term.
If it is an old house, the supply issue could be down to old galvanized water pipes that get internal corrosion, this blocks them up over time so the volume that can supply is limited. I have had it on some fittings that were badly clogged, so now I have poly fittings in the system. In old houses with gal pipe, this type of cancer can be all the way from the meter and everywhere in the walls and it costs a lot to replace it all.
http://www.single-family-home-remodeling.com/galvanized-pipe.htmlIt could also be that the infrastructure is getting older, so Sydney Water is turning down the pressure to reduce the risk of them blowing a main.
I live in a rural area, but we also have town water. The town water pressure was hopeless, so 80% of the time we run off rain water from the tanks and pump.
I have plumbed it in so that I can fill the tank from town water during the day when no one really needs water and then run pump to draw from the tanks when we need the water volume (showers, washing and baths). The feeble water pressure takes over a day to fill the small tank and then we get over 2 weeks out of that.
..... And then after 3 years they came and replaced my water meter and all the issues were cured
, although then new ones appeared as the increased pressure blew out crappy corroded joiners in my front yard
, and I also started getting water bills
If you had the time and the $$ to throw at the problem, you could install a small (2000L tank) in the back yard that is filled from the mains with a ball cock so it only filled to the required level. From this install a pump to supply the house with full pressure water when you want is. Get a pump with a pressure tank so you get full pressure from the moment you crack the tap. I don't have one, so crack the tap and I get full pressure, then it tapers off a bit until the pump kicks in and back to full pressure again. A minor inconvenience really.