Both bathrooms in my townhouse make an unbelievable foghorn/moan when you turn on either the hot or cold water. When you turn the faucets on just a little bit, the noise is immediate and very loud. If you turn them on a little more, the noise will gradually build as the water comes out. This does not effect any toilets or the kitchen faucet. Any info woul be great.

Bob

First, start with removing Aerator. Run water w/o aerator. See if the noice continues...

Turn water on in sink until the noise is loud. Then walk around to everything that has water lines and see if the noise is louder at any certain point(water softener, stops under sink, etc, etc.) There are many things that can cause this, just need to locate were its coming from before tearing into things. Hope this helps at least a little. Please let me know what you find.

I would also consider a bad washer in the faucet. Does it do the same sound if you open just the hot and then repeat with just cold?