Expert: Sharon McCarthy - 7/1/2009

Question
I have a loud sound, I think coming from the drains in our house.  When I run dishwasher or washer or flush the toilet, most times it makes this horn would.  What could it be?

Answer
Dear Donna,

 This sound would be coming from the waterline somewhere, not the drains. Generally a "horn" sound, or a chattering, or screech or jackhammering sound is caused by a valve somewhere along the waterline that is not open all the way. This can also be caused by an obstruction in the pipe, but it's usually a valve.

  The ballcock [the fill valve] in every toilet is a "valve". When those are blocked, even by a tiny pebble, the chattering and banging can be heard down the street when the toilet fills. Hose bibbs are valves. LOTS of valves. There is a valve on the line going into the water heater. There are valves on water softeners.

  If this sound is happening when you use all those appliances, I'd guess the problem is either in you main valve going into the house, or maybe, if you have a softener, it might be there. Have you had any work done lately on anything in your house that required water to be shut off?

  If so, the valve may not have been turned back on all the way. Also if any work was done outside your house, like on a line in the street, debris may have gotten into your pipes.

  You described this sound as a "horn". A horn has a reed in the mouthpiece. The sound occurs because the reed is blocking the tube in the neck of the horn. Same concept as blowing into a bottle, or whistling. Block some air and you get a noise. Same with water.

 I hope this helped. Sharon