It could be as simple as adjusting the regulator or having it replaced if it's malfunctioning. If the pressure is already at the recommended level coming into the property, then you might need to repipe the house.
Oggi Kashi - 415.690.3792 direct
Broker Associate, Paragon Real Estate Group CA DRE 01844627
All data from sources deemed reliable but subject to errors and omissions, and not warranted.
The link aboe is a good article about improving water pressure. Maybe it will help you out. Take a look.
Team Good & Miller
There are only a few things to check. The main water intake into the home may be blocked with dirt. The main intake and the rest of the water pipes may have been installed improperly with pipes that are too small in diameter (unlikely). More likely is that your water heater is old and creating calcium buildup in the tank and at the faucets. If you have filters (aerators) on your faucets you can unscrew them and tap them clean, but if it is the water heater, they'll get clogged again as the calcium makes it way back to the faucets. If you replace the water heater have the filters cleaned while you're at it.