"Ireland has soft water" is one of those things everyone repeats and nobody checks.

It is not uniform. North Dublin is quite hard. South Dublin city sits on a different supply and is much softer — you can move across the city and notice the difference in your hair inside a fortnight. Clare is the extreme case: the whole county is essentially limestone, so the water comes through loaded with calcium and it is hard as anything.

This matters more than it sounds. If you have moved house and your hair has changed for no reason you can name, the water is the first thing to check and almost nobody checks it. The signs are consistent: dullness that shampoo does not fix, a film you can feel when the hair is drying, curls that will not hold their pattern, and that strange combination of flat and frizzy at the same time.

The kettle is the giveaway. If it is furring up, so is your hair — same minerals, same deposit, just less visible.

None of this requires a water softener and a cupboard full of salt tablets, though those do work if you own your home. A shower filter costs about twenty euro. And a twice-weekly treatment properly rinsed through lifts the build-up that has already accumulated, which is the bit a filter cannot undo.

Mostly, though: it is worth knowing it is the water and not you.