Depends on where you live. Your pipes could be clogged. I think Distribution Water Maintenance will come out and check your pipes from the curb to the connection to see if it is anything they can fix before you call a plumber or something. Their number is 707-648-5235.
I live on Holly St and as long as I have lived here my water pressure has been low, My son lives by Blue Rock Springs park and his water pressure is twice as much as mine.