CurvyTap / Faucet, Tap

Did you know that turning the tapp off on the left (hot water side)
costs more money on your gas or electricity bill? Even if
you already know this; you do not always pay careful
attention to it. If you leave your tap on the “hot side”,
the tap is alwats trying to maintain the heating system
on and it costs you more money.

Putting a curved line at the bottom of the tap can be an answer.
Even though you just turn off the tap on the hot side;
it will slide and turn off on the cold side due to the curvy lines