The toilet tank cover is the (usually porcelain) piece that sits on top of the tank to cover all of the internal pieces. The toilet tank cover keeps the toilet looking sleek, while also keeping water contained, and parts in place. The tank cover does not directly attach to any parts, but instead rests on top of the tank. The only time the tank cover interacts with any pieces are if the flush handle/buttons are on the tank cover, like many of the circular push button flushers.

The tank cover is a somewhat fragile piece, and can break if it is dropped on the ground or bumped too hard onto another surface. Thankfully, toilet tank covers are not too expensive to replace, and do not require any hardware to fix. When replacing a toilet tank cover, it is important to buy the correct cover for the brand and style of your toilet ot ensure proper fit.  Toilet tanks have come a long way, with some even featuring sinks attached to the toilet tank cover, for smaller and more efficient bathrooms.