"Rust" is a specific form of corrosion - where iron joins with oxygen. Therefore, the only thing that "rusts" in water is metal containing large amounts of iron, either "iron" or "steel." A lot of things will corrode, dissolve or otherwise deform if you put them in water.
1.iron
Salt water.
steel rusts fastest in salt water.. wonder why??? because salt water has sodium which can react to iron in steel.
It doesnt. salt water usually rusts metals faster because of the mixture of salt, water and oxygen that rusts the metal, but tap water has less oxygen and no salt.
it rusts
Sweat. Sweat and water. When they get on your jewlery, it rusts.
Chemical reaction from water
anvit
Rusting is possible in the presence of oxygen and water.
All I can think of is that it rusts when exposed to water
ejecule
It rusts faster in salt water.
Vinegar being an acid rusts fast lemon juice is also acidic but very weakly.