I need help. I have a humming noise in my house and we do not know where it is coming from. We turned of the AC unit to find out if it was the unit but when it was off the noise came on several times. We then checked our water heater and pressure and it checked out ok. We also turned the power off in the house and it still came on. Does anyone have any ideas what could be causing this noise. I would really appreciate it.

Does the noise stop when you walk around a certin area of the house? Does is also do it at night or only during the day? What part of the house do you hear it most often? We had the same thing happen in our home, it turned out to be my sons friends cell phone on vibrate. He dropped it in our sofa when he cam over one evening. We heard it vibrate but when we got near it it stopped and did not happen until someone texted him again. Took two days for ust to find out what it was. If you still had the humming sound when you had the power off that rules out any fans or electical equipment. I would think you have some sort of a rodent or other animal within the wall. Perhaps bees. Mice will make noises and will stop when they hear a noise such as someone walking near them.
Do you have a turbine attic vent fan? This kind of fan only moves when the air is moving and will start and stop. Other then that I am at a loss.

You could try finding the noise with a stethoscope, or, if you don't have one (doesn't everone?) a glass held up to your ear. Put it against a wall or the floor and try to narrow down its location.

I used to work for an engineering firm. We built a new building with a metal roof and exterior walls. As soon as we moved in, people began complaining about a humming or ringing noise. Being the resident troubleshooter I was tasked to fix the problem. After a few days I figured out that whenever a large truck went by the building the noise could be heard. I never did figure out the physics of it, but I suspect vibrations caused something to resonate. I climbed all over the roof and walls looking for something loose, or a way sound waves could get into the building and sound off to no avail. The fix was to put some 6 foot wood fencing and a few 10 foot cedar trees between the building and the highway. Since then I have noticed this to happen in several metal buildings. Do you by chance have a metal roof?

Since it's not electrical, it brings to mind what happened to us: we put on a new roof, replacing the full-length aluminum venting with the new nylon mesh full length ridge cap roofing. Now, when the wind sets from a certain direction, the roof hums and even has a low moan. The other source of noises like yours can be any antennae, satellite dishes, or nearby guy wires.

Do you have, as your water source, a well? Sometimes the submersible pump at the bottom of a well will shift position in the well shaft, coming into contact with the well casing at the well head, and therefore send motor vibrations up into the house. Or, the delivery tube from the well pump to the well water holding tank could be transmitting motor vibrations into the tank, and, therefore, the house. Since the pump in a well only comes on intermittantly, when the pressure switch calls for it to pump in more water, that could easily be the source of your mysterious hum.

Whirley bird(sp?) vent on your roof?

your house is haunted!!!! ;D just kidding..yeah, it could be a host of different things, you may have a child's toy under the couch or something, or there could be some kind of crosswind humming through the house because of where the windows are located... how close are you to your neighbors? -Fishfool @ The Reef Tank

Hello

I live in Sydney metropolitan area and hear a similar humming noise. I have done all of the above; turn off power, check water pipes, etc. It sounds like a nearby air conditioner, power transformer, anything close to 50 Hz. We have underground power lines near the house which may be vibrating. It may also be an underground transformer. But then, it started around middle or end of 2006! I have gotten used to it, but sometimes around midnight I cannot sleep as well as I used to. It has to be something to do with power.
Help.