Hi,
For two months now, every week, four mornings a week at exactly 5:37 a.m., our pipes start humming really loud for exactly ten minutes and then stop, just like that. We've had the pressure regulator valve replaced and it still does it. We've unplugged the sprinkler clock and it still does it. Our plumber has had us shut off things one at a time each day that it happens and it still does it.

If you put your hand on the outside pipes (holding the regulator) you can feel the water pressure rise inside and it starts humming. We've had the DWP out to the house twice - of course it's later in the day when this is not happening, and they say nothing is wrong. None of our neighbor's sprinklers go on at this time.

We've shut the water off from the DWP meter at the street while it's happening and it stops. As soon as we open the valve back up, it starts humming again and our T-bar on the valve vibrates. This is the part that comes up from below the street and goes into our meter, not on our side of the meter. We don't think it's the mainline. When we turn off the water handle by the regulator next to the house when this is happening, the pipes still hum.

Tomorrow morning we're going to put the pressure reader on the faucet hook-up by the regulator and see if the water pressure goes up when this happens. The meter reads 60 right now. When we test it at the front of the house by the sprinkler hookup, the pressure meter there reads 120.

We think that the DWP valve by the street is worn (from 1962 when the house was built) or maybe has a hairline crack and that for whatever reason the water pressure rises for these 40 minutes per week under the street, it can't handle it and that comes up to the house.

Any ideas would be very much appreciated. Thanks!

Exorcism? Sorry - couldn't resist. Good luck to you!

Ha! Thanks WolfGuy. Our neighbor says our pipes are haunted.

Its not uncommon for the water company to deny any problems. Its common for the water pressure to surge high and low in the early AM and sometimes early PM when the rest of the street is waking up and taking showers.

The noise is always louder in AM when you wake up as typical home is sort of quite in morning as people wake up. Evening when this could also occur lots of activity drowns out this hum.

I would take note of the time in which this occurs. If it’s the same time each day insist that the water company have someone at the home at that time period to listen for themselves.

Thanks. We've been on the phone to the DWP several times. They won't send anyone out that early in the morning. It's been suggested that we install an expansion tank and if that doesn't work, a hammer arrestor.

If none of those work, it's back to square one.
Thanks for responding.

Try a letter from your attorny. That will wake them up early.

Everything points toward that city valve, but the exact time every morning makes you wonder what in the world triggers it.

Just thought I'd give an update. I spoke to someone at the DWP on Tuesday in the Field Investigative Office who actually seemed like she cared and said she would ask around. We had previously asked for someone to come out that morning at 5:37 to check the meter and were under the impression that they would come. They came at noon when I was out and left a note saying there was "No problem here. Water pressure is fine."

Well, of course it was fine at that time of day. Anyway, the pipes haven't hummed since Tuesday after I spoke to the woman at DWP and the guy came out to check our meter. I'll never know what he really did, if he fixed something or changed something.

Got a call back from the DWP lady on Thursday saying she'd asked around and no one could think of an answer. Gave us the number to the Department of Building and Safety because they regulate the water pressure in neighborhoods around the city.

Because the pipes haven't hummed since Tuesday (it's Saturday now) we're waiting to call DBS the next time it happens. My thinking is that someone knows what's going on at the DWP and because I finally complained to the right person, they fixed it. At least that's what I'm hoping. We'll see if it happens again, but right now it's so nice to sleep in past 5:37 in the morning!

They could have changed the meter. They do this one and a while. Or they may have turned the water valve in the street to off and back on which may have removed an obstruction within the pipe. All of which could change the way the water moves through the pipe.
Anyway that is good news.