About three days ago, The pipes around my electric hot water heaters started making continuous moaning noises. I've heard similar sounds when there's air in the line, but have alleviated that by running water until the bubble comes through. That has not worked. The water heaters are about 6 years old, the same age as the house. Meanwhile, there is extensive highway construction nearby. They already cut the water main twice. Could it have to do with that? Please help, this is driving us all nuts!

It sounds like some pebbles got sucked up into your system and are now vibrating against the pipes. Fell where the vibration's the loudest and then shut the water off, open up the pipe and flush it out. Good luck. Tom