I work in a chemistry lab. In the basement, we have a water purification system that provides deionized (DI) water to every sink in the building. We also have a few commercial water purification systems attached to individual sinks. These commercial systems do slightly improve our "house" DI water, but there isn't much difference.
Many of our clients need DI water to prepare the quality control samples that accompany the samples they submit to us. Since we produce plenty, we let them come into the lab every so often and fill up a container at one of our sinks.
One day, a client comes into the lab I'm working in, carrying a big, empty carboy (That's a fancy word for "jug," for you non-science types.). It was obvious she had come to get some DI water, so I directed her to one of the two sinks in the room. But she refused. "I need to get water from *that* sink," she insisted, pointing towards the other sink.
She would really be in the way at that sink, so I tried again to get her to go to the other sink. The water is identical at both sinks. She said, "I was told that the water at *that* sink is the best water in the building, and to always take my water from that sink."
I was confused for a minute -- who would have told her that one sink was better than another? Then it dawned on me. "Ma'am, the better water at that sink was from the commercial water purifier mounted on the wall above it. But, as you can see, it's labeled 'Not in Service.' It's broken, and we've determined that it's not worth the expense to repair it. But our house DI water is excellent, and should be just fine for you, and it's identical at both sinks."
"No I've never used that contraption on the wall. I just take the water from the sink." (The water from the commercial system comes out a different tap, mounted on the system.) "Now, I need water from *that* sink. It's the best water in the building."
"Ma'am, the two sinks produce identical water. They even come from the same water main, there in the corner."
"No, they don't. They told me *that* sink has the best water in the building. I need that water."
"Ma'am, I'm sorry if you misunderstood whoever told you the first time, but it was the commercial purification system that produced better water, not the sink. And that system is now broken. The water from either sink will be fine for what you need." She's apparently been using house DI water all this time, anyway.
"No, it won't. I need water from *that* sink."
"Ma'am, I can shut off the DI water valve for the room if you'd like, to prove that both sinks get their water from the exact same pipe."
"*That* sink has the best water in the building."
In the end, it wasn't worth the fight. We just moved all of our stuff to the other side of the room so that she could use the sink she wanted without being in the way. And this person is supposed to be a scientist?