There’s nothing wrong with this tap — it is the users that are using it wrong!!

Alexander Miller
5 min readJun 9, 2021


There’s something wrong with the design of this tap, its dangerous!! — yes its a standard boiling water tap that have appeared in offices and its fantastic for making a quick cup of tea ☕️ there is a separate debate to be had about the right temperature for brewing tea effectively, but thats not what concerns me now.

The designers are aware of the danger involved in dispensing very hot water and have created a lock feature depicted with a padlock 🔒 icon, so that you cannot just dispense water, there is an interruption in the process to hopefully make you think about what you are about to do. Which works quite well for this purpose once you have worked out the way to operate it.

So why is it dangerous?

Because this happens — some people who are right handed end up reaching across the under the boiling water — it looks dangerous as their hand is so near the boiling water and it does not need to be if they used the tap with their left hand. And it wasn't just one person it was quite a few in the time that i was noticing the tap. One person told me that they had burnt themselves five mins ago using the tap. So what is going on here?

Hypothesis 1

My initial hypothesis was that the control for the tap is on the wrong side for left handed people, as the predominant hand for each person is free in the task of making a cup of tea, leaving the right hand to hold the tea cup so that they can get a tea bag and open cupboards, fridges etc with their right hand. and operate the tap with their left hand.

Test 1

Based on my initial hypothesis I wondered if people had an override when it came to holding cups and would not use their dominant hand, so that the other could be free to do other things. The test I devised was to get people to pick up objects — a pen and a cup that they were about to use and record which hand they used.

I invited 8 people to take the test, I asked them to draw a circle on the page and then pick up the cup — here are the results.

Something was going wrong with my test. See lines in pink, some people were not picking up the cup in a different hand. There was also another issue with my approach. In some cases where I had asked the participant to pick up the cup while they were still holding the pen. Also they were not drinking out of the cup, they were just picking up a cup — is there a difference here?

However this then led me to the second hypothesis.

Hypothesis 2

Does the cup end up in a certain hand due to the sequence of events that have occurred previously or what your about to do next, not just based on the use case for the cup. — Unfortunatly Iran out of time to this idea.

An epiphany

It occured having observed a number of users that what is important here is that the tap was not working for all of the users, regardless of the reasons why they were using different hands to operate the tap. If the control is placed on either side of the tap, it would be a problem for some of the users, who would end up reaching across the stream of boiling water.

Interestingly this problem does not appear with older products that provide boiling water on demand.

Here the tap is above and works equally well for right and left handed cup holders, as well as there being no danger of scolding yourself whilst operating the control. (The hand holding the cup getting scolded is a different issue).

I wonder how the tap was user tested or how it got released to market, as in real usage scenarios it is not used in the way that the designers intended and is potentially dangerous.

Pictured left is the Zip Hydro Tap which has been designed in a way that it does not matter if your left or right handed your hand does not get near the flowing water whist operating the control.

With a human centred design approach the designers intention would not have been a factor, as very quickly through effective testing, where users were observed using the tap in context they would have discovered that for some users it was not safe. This should have prompted a design rethink.

Being human centred in your approach means you are no longer designing a tap but a method to safely dispense boiling water for all of the potential users of the tap. This shift in focus opens up new possibilities to build something that really meets the users needs.

Do taps matter? — it does if you have just been burnt by boiling water!!



Alexander Miller

I’m a UX Designer with a background in Business Process Analysis. A Lean Six Sigma Blackbelt, Agile coach & ScrumMaster. Im a big fan of self organising teams.