Usually clogged shower heads. Turn water off and shower off. Screw shower nozzle off by hand or with pipe wrench. Turn water and shower on with nozzle head off if water flows clean or replace nozzle. If water pressure is still too low with nozzle off check shut off valve and open valve more. Make sure main water shut off for your house is open enough to allow adequate water pressure.
the outlet pipe at the base of the shower has not got enough angel for the water to run free
The downward movement of the water in the shower creates downward movement in the air inside the shower area. Air flow causes low pressure and so the air pressure from outside the shower area is able to push the curtain inwards.
A flow meter.
to much water flowing through shower valve will cause whistle in pipes.try a new shower head with less flow[gallons per minute]amount should be on head somewhere try 2.5 gpm or less
to conserve water
Did you remove the shower head and check for a flow restrictor or mineral deposits blocking the orifices
To prevent any back water from the shower head and also the water contamination into system.
To conserve water.
Yes, you can install a tee in the riser. The pressure loss will be minimal since both shower heads will have a flow restrictor unless you remove them. If you remove them, you probably wont notice any difference. If you do notice a difference, put the flow restrictor back in the closest shower head to the shower valve.
Standard high-flow aka unrestricted shower heads made before 1995 were water-guzzlers. As of 1995 shower heads must be low-flow, with a rate of 2.5 gallons per minute.
More "VOLUME" flowing from the tub spout then the shower head as the shower head has a flow restrictor
depending on your spout diverter if its a valve or is it on the spout it self, if the diverter is on the spout then your diverter is not letting full flow of water out of the spout and its putting enough pressure to allow the water out of the shower head, I had this problem before and if you change the spout it should fix the problem. If you have a 3 way valve which is on the wall then i would suggest replaceing the parts in that valve if possible other wise change out the divert valve. If your broke like me and want a cheap fix then put either a water flow resistor or a shutoff right before your shower head.