According to the tour guide at the Guinness Storehouse in Dublin, the belief that Guinness tastes better in Ireland is not just an urban myth. He offered two explanations for the phenomenon.

1. Freshness

Because Guinness is so much more popular in Ireland than elsewhere, kegs don’t last long. So your pint is more likely to be fresh.

2. Cleanliness

If you’re a pub owner in Ireland, you are affiliated with Guinness. One of the terms of that relationship is that every three weeks you’ll receive a visit from a Guinness representative who will flush the lines to your Guinness taps. Pub owners are supposed to do that on their own, but some are lazy about it and Guinness doesn’t want to take any chances. If the lines aren’t flushed, the brew will be compromised.

What a savvy business practice!

On the way home, in the airport, I got to see it in action. These taps have signs on them that say Line Cleaning In Progress.

And here’s the Guinness rep flushing the lines. I asked him how often he shows up to do this, and he confirmed the story. “Every twenty-one days.”

The only problem is, knowing this, how can I ever again order a Guinness at home?