Showering with low water pressure doesn't just fill right, takes a long time, and may even waste water in the long run. Some causes of low showerhead pressure are easier to fix than others; the diagnosis will tell you what you are dealing with. Here are some of the common causes of low showerhead pressure:
Clogging is probably the most common cause of low shower pressure. The clogging can either occur within the pipe delivering water to the showerhead or the within the showerhead itself. A common cause of clogging is mineral deposit accumulation, which is common in areas with hard water. The debris accumulates and either blocks the showerhead holes or reduces the width of the delivery pipe, hence lowering water pressure.
Physical damage to the delivery pipe may also result in reduced showerhead pressure. For example, if the pipe gets crushed or bent at some point, the damage will reduce the diameter of the pipe at that point, and this will reduce the rate of water flowing through the pipe. Another example is if the pipe breaks or crack; this will reduce showerhead pressure because some of the water headed for the showerhead will be diverted through the cracks.
Malfunction of the Pressure Reduction Valve
Contrary to popular belief, high water pressure isn't necessarily good. Extremely high water pressure can cause plumbing leaks, shorten the life of your water heater, or even cause your hot water tank to explode. This is why some houses have a pressure control valve installed at the point where the main water line enters the home; you can use this valve to reduce or increase water pressure anytime. However, sometimes the pressure control valve malfunctions or fall out of adjustment, lowering your water pressure. If this is the problem, then you should witness low pressure at all points in the house, and not just the showerhead.
Diverter Valve Malfunction
A shower diverter valve does exactly what its name suggests; it diverts water from one different bathroom fixture to another. For example, it can be used to divert water from the overhead showerhead to a handheld shower, or vice versa. It can also be used to divert water from the showerhead to the bathtub faucet, and vice versa. A malfunction in this valve may reduce water flow in one direction thereby causing reduced showerhead pressure.
Consult a plumbing service like Roto Rooter Plumbing & Sewer-Drain Service for a professional diagnosis if you can't figure out why you have low water pressure in the shower. It might be that you are dealing with hidden water leaks that may cause even more problems if not fixed in time.