We have been in this house since it was built in '71. No problems until it was re-piped 2 yrs ago. Since then, we have a humming or whining every time one of the 3 outsides spigots is used. I thought this was air in the system and would work its way out, but it hasn't. As the water enters the house, there is a T, to allow inside water to pass thru a water softener, whereas outside water is piped directly to the 3 spigots. There is no problem with the inside water, but the outside whines from any spigot, and changes tone when increasing or decreasing the flow. We have no pressure regulator and pressure is aprox 68#.