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"My toilet is a fog horn!"

Column #821 11/13/2010

On The Level
Jim Rooney

Q. I have been having a problem when flushing a toilet on the first floor of my home. The sound after the tank fills could be described as a “fog horn”. The second floor toilet is not a problem. A neighbor told me I have air in the line which is the cause of the sound. Could you possibly explain the problem before I call a plumber?.

A. Toilets are one of those magical devices that make our modern lives livable. In one form or another they have been around for thousands of years but the current incarnation, one that flushes on command then sits completely idle until needed again, only dates from the last half of the 19th Century when the city of London England was being populated with toilets that rather than flush on command, ran water constantly.

The Fire Service of London, having had a very bad experience in 1666 when the whole city nearly burned down, were fearful that these constant flush sanitary devices would so deplete the city’s available water pressure for fire fighting that something had to be done. So the sanitary engineers of the day got to working on the problem and installing of flush and filler valves plus the inherent design of the trap and bowl holding water was born. The person most associated with this innovation is to this day-- I’m not kidding-- was Thomas Crapper. His contribution was the filler valve and his name was stamped on the device and our World War I doughboys passing through England on their way to fight in France saw the name and, not wanting to use the lightweight English term “loo” to describe the device, named it the crapper. Seven generations later poor Tommy Crapper’s name is still associated with the flush toilet.

The modern filler valve begins to replenish the water in the toilet’s holding tank the instant the flapper or flush valve is opened to dump the contents of the reservoir tank into the toilet bowl resulting in the flush. As the water fills the tank the filler valve itself is controlled by a float that slowly turns the water off when the tank fills to a preset level. You can look in many toilet tanks where the manufacturer has cast a line in the porcelain on the rear of the tank and labeled it “water line”. The float valves are adjustable somewhat and when set to shut off at that line ensures just enough water dumps into the bowl to get the job done.
Two things I’ll bet are true about your noisy toilet. First it’s an older model and next it’s the most frequently used toilet in the house.

What’s happening is the valve seat of the old filler valve is slightly degraded from long term use and as the valve approaches the very end of its closing to shut off the water a phenomenon called sonic cavitation sets up and creates a sound. The noise can present itself in many different tones, much like the tuning of whistle. I’ve heard them scream like a banshee or, like yours, moan like a fog horn. And your neighbor was on target but he just wasn’t too sure of the air source because if there was air in the plumbing line itself it would show up elsewhere as well like faucets and showers.

Is it a problem or will it damage the plumbing? No, it’s just an annoyance. If you wanted to eliminate the noise you would just need to replace the filler valve. If you’re a decent enough do-it-yourselfer you could do the job yourself. It entails shutting the water supply off at the valve usually down left under the toilet, emptying the water from the tank and installing a new filler valve, obtainable at any hardware store or home center. While you’re at it, grab the bowl and rock it back and forth. If it moves a lot then consider replacing the wax ring and tightening the bolts so it doesn’t move. Be careful doing that because you don’t want to accidentally over-tighten the bolts, breaking the base of the toilet. Which brings me to my last piece of advice: if you do the job yourself, don’t do it on a weekend because if you get into deep trouble you’ll want to 911 your plumber to bail you out.

Keep the mail coming. If you've got a question, tip, or comment let me know. Write "On The Level," c/o The Capital, P.O. Box 3407, Annapolis, MD 21403 or e-mail me at jimrooney@jimrooneyonthelevel.com or inspektor@aol.com.

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