Water for baths, sinks and basins can be provided by separate hot and cold taps; this arrangement is common in older installations, particularly in public washrooms/lavatories and utility rooms/laundries. In kitchens and bathrooms mixer taps are commonly used. In this case, hot and cold water from the two valves is mixed before reaching the outlet, allowing the water to emerge at any temperature between that of the hot and cold water supplies. Mixer taps were invented by Thomas Campbell of Saint John, New Brunswick and patented in 1880.

 

For baths and showers, mixer taps frequently incorporate some sort of pressure balancing feature so that the hot/cold mixture ratio will not be affected by transient changes in the pressure of one or the other of the supplies. This helps avoid scalding or uncomfortable chilling as other water loads occur (such as the flushing of a toilet). 

 

Rather than two separate valves, mixer taps frequently use a single, more complex, valve controlled by a single handle (single handle mixer). The handle moves up and down to control the amount of water flow and from side to side to control the temperature of the water. Especially for baths and showers, the latest designs do this using a built-inthermostat. These are known as thermostatic mixing valves, or TMVs, and can be mechanical or electronic. There are also faucets with color LEDs to show the temperature of the water.