Typically the reason for this is there is back pressure in the pipes. The water should not run out of the other faucet(s) for long, and should stop after a little while. This back pressure is the same thing that the plumber or swimming pool installer wants to avoid, and thus the reason for leaving the taps on when turning the water off. Once the water is off in the home, you still need to run some of the taps for a little bit. Let any excess water still in the system run off, this will also get rid of any pressure still in the system as well.
When do I need to shut off the water in my home, if I am installing a hot tub or swimming pool?
Unless you are having piping ran to your water lines, you do not need to shut off the water in your home. If you are having an installer or contractor install your swimming pool or hot tub, they will likely notify you whether the water needs to be shut off or not.
These questions are answered more in-depth on the swimming pool & hot tub piping installation page. This page will answer many questions about when it's required to hook up piping for your hot tub or swimming pool. As well as that, one question that persists is - do I need to shut off the water when hooking up piping? Who can hook up my pipes for me - do I need to call a plumber?
How does pressure work in my pipes?
Pressure builds up in your pipes - air pressure, that is. The main concept of turning off the water in the house is to get rid of the air pressure. Any remaining air pressure will come out of an open faucet, with water. So after you turn the water off, you'll want to open the faucets in the house and let all the water and air pressure drain out. That's how air pressure works in your plumbing. Run the faucets in the home (open them all) until all the water has stopped. Then the water has drained out that is still in the pipes along with any air pressure.
What if the water does not stop running after I have turned off the water valves in my home?
This does not happen - at least, it's not supposed to. If you have shut off the water pressure in your home and you still have water coming out of the faucets, and you have tried running the faucets for a few minutes, then the following may apply. You may have used the wrong shut off valve for the air pressure. Or, there might be another problem. Likely best to call a plumber and see where the problem lies. More then likely though you just have the wrong valve.
