I was in the fifth floor kitchenette at work, watching Dave fill up his plastic cup of water. When he finished he turned to me, expectant and uncertain. Clearly, he sensed the ‘I want to say something to you’ vibe of my loitering.

Indeed, there was something I wanted to ask. I have spent the past year watching people fill up plastic cups of water in the kitchen. People would take a plastic cup, fill it, drink from it, then very conscientiously place it into the plastic recycling bin. Meanwhile, two shelves of perfectly reusable ceramic mugs hovered above the filtered water tap.

My company is full of environmentally friendly people, yet despite recurring requests, the stacked column of plastic cups continues to be replenished.

I wanted to ask someone about this. Today was my lucky day because Dave is a nice Englishman and probably wouldn’t be offended.

‘Dave,’ I said. ‘Is there some reason you use a plastic cup instead of a mug? Is it…’ I paused, ‘…a cultural thing?’

Dave looked surprised, then lifted up his cup of water and gazed at it for five seconds.

‘I don’t know,’ he began. ‘I guess I wouldn’t drink water from a mug. I never thought about it.’

So he thought about it. ‘I think it is a cultural thing. I feel like I need to drink water from a clear cup.’

Now this was something that hadn’t occurred to me! I had speculated to myself that there was something wrong with having a handle on the cup, or that mugs were too big for water.

‘Oh! Thank you for that,’ I said.

Later, I tried to corroborate my findings with Chris, another Englishman.

‘I use a mug for water,’ Chris said. ‘But I can see why others might not want to. I think it’s because mugs are sometimes stained. When you have tea or coffee, then you don’t mind because you can’t see. But because water is transparent, the staining probably puts people off.’