What is the best way to regulate the pressure in my master bathroom shower?
Most shower heads now days have a water saver in them. If you unscrew the shower head from the shower arm and look in the threaded end you should see a screen or a small piece of plastic or metal with a small hole in it. This would be the water saver. Take a small screw driver and pry it out, your pressure should improve, even if you buy a new head, it will also have the water saver in it. If this don’t work then I would check to see if the problem is on the city side. Sometimes the water company will slow down the presure to a older nieborhood where the pipes may give way under normal presures. Also check to see if the problem may be in restriction from hard water deposits in the pipes. But nine times out of ten it will be the water saver in the shower head.
Assuming you are looking for more water pressure, and you have removed the flow restrictor from the showerhead and there are no obstructions in the waterlines, you can upgrade the typical 1/2" water lines to 3/4" water lines and install a 3/4" mixing valve and a 3/4" diverter. All of the above will insure the highest pressure/volume you can get from your showerhead.
It could be a variety of things. First, I would start at the water saver inside the head. If it is still there remove it. If that doesnt work, remove the face plate of the shower valve to research if the valve you’ve got has its own shutoffs. If it does, make sure they are fully open. If that doesnt work, I’d recommend checking to see if maybe you have isolation valves just for the master bath? If so make sure they’re open
Before doing anything determine the cause of problem for pressure. First you check all the pipes which are used in bathroom. Low water pressure can be poor plumbing within a house. Unscrew the aerator with pliers. Check isolation valves are proper.