A shower diverter (sometimes called a bath diverter) is the part of the tap or shower that switches the water flow between two outlets, although this can sometimes be more than two outlets.
A good example of a shower diverter is in a traditional Edwardian or Victorian style bath mixer where there is a lever that moves side to side switching the water flow from the spout to the hand-held shower.
Another sort of diverter is a pull up design where a knob is pulled up on the bath mixer tap, to switch the water flow from the spout to the shower handset, then dropping down for the water to come out the spout again.
These two diverters tend to be most commonly found in bath mixer taps.
Shower diverters which rotate into different positions tend to be found in shower valves and in wall shower panels. These serve the purpose of switching water flow between different outlets such as from an overhead shower to a hand shower or from a spout outlet to a shower head.
In all cases a diverter simply switches direction of the water. The water temperature control and on/off flow will be controlled separately.
Like any working part, these will wear out or fail with time, but fortunately replacement parts are available for many different situations. To help we have created a category of replacement sleeves and levers, pull up diverters and long stemmed shower cartridges for use in ready installed showers. Please take a look here.