What could cause a constant loud whooshing sound in the water pipes like rushing water even when faucets are closed and there is no water leak anywhere?

Answer 1

You may have a leak you dont know about. Check with the Water Utility - somtimes they will come out for free. Yep, they will. If you hear water and nothing is turned on, you have a leak. Shut off your water from inside your house (shut-off is located where your water line enters the house). If the whooshing goes away, the leak is inside your house somewhere. If it still makes the sound, the Water Utility will shut off the curb stop. If the whooshing stops, then the leak is between the curb stop and your main shut off (ie. there's a leak in your main service line coming into your house). In general, it will be your responsibility to make this repair as it is on your side of the curbstop. If the sound persists, it is coming from the public water main and Water /utility Crews will locate with a stethoscope and make the repair at no cost to you.