Toilet flushing causes gurgling sound from bathtub drain

No, it's not normal.

A proper "vent" connection is supposed to prevent this from happening.

There is quite a good explanation here w/pics:

Jim

"Sounds" like a faulty vent.

Yep, but a blockage in the drain can sometimes cause this depending on how the plumbing is connected. Snake the drain. Then check your vent stacks for blockage.

Thanks for the replies. So if this is a vent problem, what sort of labor is required to fix it? And what are the disadvantages of not fixing it?

Would someone have to go into the wall or simply fix something on the roof? Sorry, newbie here and any help would be greatly appreciated.

Bad smells as your toilet can suck the other traps dry letting sewer smells come up.. Your vent probably exits your roof. Once we had to fashion a long pipe to vacuum/blow out the stack. It was cheaper than busting down bathroom or bedroom walls.

I see, so this sounds like a blocked problem. I hope it's an easy fix and not one that requires going into the wall. So can this be a bad installation problem?

Often using a hose to blast some water down the vent from the roof works. Some birds like to build nest in them. How difficult it may be depends on where the problem really is and what it blocking it.

It can be. Sometimes designing good plumbing is an art. First check to see if your bathroom vents out the roof. If not you might have a autovent someplace in the walls.

ok, I had better leave this to the pros. Thanks everyone, will investigate.

Autovent or air admittance valves are only used on sinks. There must be a roof vent.

Easiest thing you can do is stick a hose in the roof vent (or vents) and flush, it should run directly to the sewer and not backup anywhere in the house if there is no bad plug. Next would be to snake the vent and drains or you could just start there.

Anyway should be possible to fix without breaking a wall but figuring out where the plug is in the hidden piping network does take experience to know what to expect and where to look for it. A plumber can snake from any drain, vent or cleanout plug, its just a matter of finding the right one.

People have been known to break the law. Especially when installing an extra bathroom in their basement.

If its a straight down(from the roof to behind the toilet) vent pipe, I'd tie a large nut on a string and lower it into the vent and see how far down the obstruction (if any) may be. If its a bird nest, close, I'd try to PULL it up with my shop vac instead of pushing it down further. If its a tied together vent system that runs sideways in the attic at any point...well forget the string theory.

Smart move, you may save yourself some money.

The tub in our main bath does the same thing, and we were very concerned until our plumber (who lives seven doors down) said it's perfectly fine, it's a side-effect of the way the bathroom pipes are tied into the main stack. When the toilet flushes, the rush of the water down the pipes creates suction and what we (or you) hear is the vacuum in the pipe pulling air through the trap in the tub.

When the toilet flushes, the rush of the

Therein lies the problem. It SHOULDNT be pulling air thru the tub trap.

That's why it's supposed to be vented.. THATS where the air is supposed to come from.

That was my thought as well. If there is suction, wouldn't the tub trap be useless?

Ah, yes, grasshopper, but in 1952 the plumber(s) who built our neighborhood evidently didn't believe in such a thing. Thus, the thundering tub drain, which is especially nice at 3 a.m. when the Wife gets up to go to the bathroom.

BTW, since we're on this subject, the plumbers installing the piping for the new bath we're installing in our rental house put the vent inside the wall, and then cut a hole into the adjacent walk-in closet. Am I going to get sewer gas smell inside the closet now?