I have a Waterpik hand held shower head (that looks like this) that leaks a significant amount of water down the hose when I first direct the water up to the shower head. It's not leaking from where the pivot ball connects to the pipe. It's leaking from the end of the hose that connects to the pivot-ball bracket.
It seems to be related to water pressure. Our water pressure fluctuates some (due to the pressure tank below the house refilling from the well pump when the pressure drops too low). When I first divert water from the tub faucet to the shower head, water comes running down the shower head's hose for several seconds, some of it often making it out to the bathroom floor. Eventually, something reaches some threshold, and suddenly the water switches to all coming out the shower head. I believe this happens when the water pressure gets high enough, because when the pressure drops (such as when a toilet flushes), it can start coming down the hose again.
I have checked/wiped-off the seal between the hose and the bracket, and I don't think that's what's leaking. My guess is that the vacuum breaker in that end of the shower head hose has enough debris/silt in it that it takes more water pressure than it's supposed to in order for the seal to close and the water to therefore be directed out the shower head. (Our water is somewhat silty, despite having a house filter between the well and the pressure tank).
If that is the cause, is there a way to clean/fix the hose, or am I out of luck and will need to simply buy a replacement?
