Taps are an everyday item that comes in a great variety of designs. Unfortunately, this can lead to usability issues. But, first let us focus on the user requirements for a tap. At minimum a good usable tap should indicate the following:
Design criteria for a usable tap
- Whether the water flow starts manually or automatically (e.g., motion sensor). An icon with a hand and two lines marking the motion sensor clearly indicate an automatic tap.
- Whether the water temperature is adjustable (photo below, 2 and 3) or fixed (photo below 4)
- How to adjust the temperature. For example, adjustment before the water flows through rotation of the button on top in photo 2 or while the water flows through movement of the handle in warm or cold direction in photo 3.
- For manually operated taps, how to start the water flow:
- push the handle (photo below, 2) or
- pull the handle (photo below, 3) or
- rotating of the handle in (photo below, 4))
A usability fail
While visiting friends I found another interesting tap design (photo below). Their shower had two taps, one for cold water and one for warm water. The taps were colour coded. A blue dot indicated cold water and a red dot indicated hot water. So far so good. However, the colours were on the side of the taps, impossible to see from the top. Users either have to memorize the position of the colours or they are doomed to find their water temperature by trial and error. If that would not be difficult as such, the two taps have inverse opening directions. One tap opens when turned towards the user and the other when it is turned away from the user. My friends told me that they it is a nightmare to find the right water temperature.