I recommend that everybody turn off their shower head whilst shampooing/lathering. I find that this is easier to do in showers with a hot/cold mixer, as the time/water it takes/wastes finding a comfortable temperature each time with separate hot and cold taps tends to waste more water than it will save.

To wash basins, however, I recommend separate hot and cold taps be installed to a single faucet, as every time a mixer is turned on when its not completely pushed to the cold side, it will be unnecessarily drawing water from the hot water system. This will most often go unnoticed, as by the time the hot water comes through, the person has finished washing their hands in what they thought was cold water and has turned the tap off.

Meanwhile, the hot water that was summoned from the hot water system remains in the pipes and turns cold and the hot water system is already busy drawing in more cold water to replace that which was not in fact ‘used’, but completely wasted.

If you do have a mixer already installed to your washbasin faucet, resist the urge to leave the temperature control in the middle just because it looks better. Something to think about.