Water Heaters - Cold water to tank when toilet flushes?

Why does it sound/feel like there is water moving through the cold water supply line in my water heater when I flush my toilet? And afterwards,the cold water pipe is warm to the touch. Am I just feeling flow from other parts of the plumbing system?

With the info. that you provide, it sounds like the toilet is hooked up to the hot line, best that I can do.

It isn't hooked up to the hot line. Is the toilet very close to the water heater? That is what it sound slike in which case it isn't completely unheard of...i wouldn't worry about it unless it is a loud noise that is driving you crazy or is causing problems somewhere.

could you clarify what you mean by:

And afterwards,the cold water pipe is warm to the touch.


which cold water pipe?

the feed to the water heater?

if so, how far away from the heater is is getting warm?

Run the hot water in the bathroom sink until the water is hot and then flush the toilet a few times. Feel the water in the tank. Is it hot or just warm? If it's hot then obviously it's hooked up to the hot line. If warm you could have crossover condition in one of your plumbing fixtures. If that were the case though I would think you'd be seeing other things as well. (CSG's and nap's scenarios make a bit more sense if it is close)


Just a curiosity thing:

I've seen a few toilets in other people's houses connected to the hot line. (I thought this was against code nearly everywhere, but...) Why would someone do this?

Can think of a few guesses but would love to know the real reason:
- Eliminate condensation on the toilet
- Prevent hot line from freezing in the winter
- At one point a bidet attachment was used and they didn't want to run a separate line
- The previous owner liked to wash his hands in the toilet bowl

I think that is called 'plumber screw up' heh. I've seen hot water run to toilets as well...matter of fact i can think of about 12 years or so ago when i did it myself (was a screw up on underground rough lol).

Is it against code? Not in my book...is it practical or make any sense? Nope.

the only reason I have heard of folks running hot to the terlet is to prevent condensation on the outside of the tank. One of the problems with that is there typically isn't enough flow (1.6 gal) to allow the hot water to reach the tank anyway so it simply becomes a waste of energy. You run hot water out of the heater and it provides no benefit anywhere.

==============

- At one point a bidet attachment was used and they didn't want to run a separate line
- The previous owner liked to wash his hands in the toilet bowl

you would still need a cold to the bidet as well, unless you want really hot "stuff". Don;t see much sense in that idea.

as far as washing of the hands.....what part of the country do you live in core???????????????????????

Hehe it was of course just a joke nap!

Although my bathroom sink _is_ currently broken. If I didn't have a bathtub spout in that bathroom, hmmm.....

I'd use the kitchen lol before the toilet.

I don;t know if it would make a lot of difference. Have you seen the story about the girl that did a science fair project where she compared the bacteria levels from a toilet to the ice machines at fast food restaraunts? Guess which had more bacteria? and it's not the toilet.

http://www.slashfood.com/2006/02/15/fast-food-toilets-cleaner-than-ice-machines/

Yeah...but they say a dogs mouth is cleaner then a humans. That doesn't mean im gonna start french kissing my dog instead of my GF :).

But my dog is available if any one on here is interested :)

CSG: The original post said that he had flow thru the water heater when the toilet was flushed, that indicates that hot water is being drawn from the hot side. The additional clue is that the supply is warm to the touch, sorry but I disagree with your post.

Thats why it is good Shacko that we have multiple people giving advice so hopefully one of us provides the correct answer to solve the guys issue. :)

Sometimes i'm sure we're all wrong. Hopefully he'll post back soon about whether or not he has hot water in the toilet.

My thought is that the toilet is close to the water heater. If he is on a well system with a pump..when he first flushes the toilet water is gonna flow from all directions (equal pressure) until the pump pressure switch activates and starts re-pressurizing the house. In which case if the toilet is next to the water heater it is possible to draw water back out of it slightly.

This was my thinking...but the Op hasn't answered our posts to clue us in a little.

It is possible that if the cold water connection to the toilet was physically very close to where the hw tank was connected to the supply line a small amount of water to syphon back from the tank.

I'm not a licensed plumber but I know that the instructions for water softeners I have installed warned of this possibility and had specific details on how far they should be apart.

This only make sense if you consider that when a tankfull of water heats to 140 degF that it will expand slightly and backfeed a bit when the supply is opened elsewhere.

If this is a problem you could relocate the connection for the toilet or install a check valve on the tank.

Oh hello everyone, wow I had not seen this thread blow up like this.

Anyway, yes the toilet IS very close to the water heater. I will do the experiment with the sink and seeing if there is hot water in the tank. I do not think there will be ...seeing as how when I had the water hammer issue, the vibration was through the cold water line FROM the very same toilet.

Probably me just being paranoid, will check.

Hey! Cold water running into toilet tank, so I guess we're all good. :)

Sorry to waste everyone's time, but it was a fun thread I think...at least we found out something interesting about ice machines ;)