The overflow tank is either cracked or its overheating and leaking from the cap
check to see if the overflow bottle cap is in 2 parts allowing antifreese to escape the overflow tank system when the engine is running your car might also be running cold all the time even though the overflow tank shows full
from your overflow valve
You may have a bad radiator cap.
An overflow pipe on a (toilet cistern?) will leak if the rubber disc in the ballcock slide valve needs to be replaced.
bad radiator cap
Yes. You will know if your car starts leaking it massively. And it will overflow.
woot woot
It could be the coolant overflow tank that is leaking.
Either the flapper in the bottom of the tank is leaking or the water level is too high and it is running down the overflow tube.
float overflowing after replacing throttle cables / why?
If leaking at toilet flange, wax ring needs replaced.