My mother-in-law keeps a large jug next to her sink and it only occurred to me a couple years ago to ask her what she uses it for. She fills the jug with the water that comes out of the tap before the hot water comes through when she's filling the washing up bowl. Why hadn't this occurred to me sooner?!?! All of that perfectly good water - gone - down the drain.
Instead, use that water to fill the kettle, fill your water purifier, fill a saucepan... whatever... just don't waste it! This is a very easy money-saving tip.