* Shut water off to downstairs toilets
* Does water sound go away?
* If yes, turn the water on to one of the toilets.
* does sound return?
* If so, replace the water valve in that toilet.
* Do the same test for the other toilet.
* The rubber of plastic ring that allows water to enter the tank or shuts off the water becomes weak and reacts to changes in water pressure.
* good luck… Adios… Jasper
Jasper Castillo