No need to turn off the faucet, just install the FaucetPal

https://www.greenmatters.com/p/how-to-save-water-at-home

The first water saving tip from Greenmatters is to turn off the faucet when washing hands, shaving, etc.  We have an easier solution - just install the FaucetPal.  The FaucetPal will turn your faucet into a zero waste faucet.