Is there not currently a charge for it (other than general taxation)? Metering is orthogonal to privatising - you can be metered or not in the UK, it's usually cheaper to be on a meter.

No, so each household has an allowance, to avoid obviously exploitation.

For example 0-4 residents have an annual allowance of 213,000 liters. Anything above that is charged at €1.85 per 1000 liters.

Note : The average amount of water used by a household in Ireland is 125,000 litres per year

These are majority unmetered at the household level so it's not clear to me at least how it's measured.

https://www.citizensinformation.ie/en/housing/water-and-coas...