If you have the spray head type, I had the same problem...called Grohe. They said to remover the pressure regulator. Take off the spray head, and just inside the end where the water comes in, you will see a white plastice thingy. Remove it. They said you can do it with needle nose pliers, but I had to pry it our with a tiny screwdriver. It came out in pieces, but once out, the water pressure is GREAT!