bottom of a tank may not cause an immediate problem. However, leaving foreign objects inside a mechanism that relies on moving parts and reliable seals is unnecessary.
Potential concerns include:
Interference with the movement of the float or fill mechanism
Obstruction around a valve or other component
Complications during maintenance or repairs
Misleading confidence that a plumbing problem has been fixed
The most important point is that the hack offers no established benefit to justify introducing an object into the tank.
If you’ve already put foil in your toilet tank,
