Toilet fills when sink runs

[Orrian]

Toliet is filling when my sink runs. I pretty much have a good idea. Someone break the bad new to me please.

 

[Twowaxhack]

If the toilet bowl is filling up with water as your sink drains, that indicates a branch main or the main sewer line is obstructed.

 

[Jeff Handy]

There is also a good chance that the wax seal under your toilet will be slightly leaking from this sewer backup.
So if you let it go on too long, you might be rotting the sub floor in the bathroom,
or leaking water onto any room below that toilet.

 

[Orrian]

Its when I turn the sink on and off I can hear the toilet tank taking in some water for a few seconds.

 

[Orrian]

Its when I turn the sink on and off I can hear the toilet tank taking in some water for a few seconds.

Oh you are saying the drain from the sink my be pulling water from the toilet?

 

[Jeff Handy]

We thought you were saying the bowl was filling up.
If the tank is filling up, then change the fill valve inside the tank.

 

[Orrian]

Question is how is my sink triggering the fill value in the toilet. The other upstairs sink in the other side of the wall almost triggers the toilet.

 

[Jeff Handy]

The fill valve has gone bad.
The pressure in the supply line drops when the sink faucet runs.
Change the fill valve.

 

[Orrian]

The fill valve has gone bad.
The pressure in the supply line drops when the sink faucet runs.
Change the fill valve.

Thank you just wanted to understand. I will get to that asap. And thank you again everyone