Is the water safe to drink?
In almost every circumstance, very much so!

As you travel around Ireland you will notice slightly different flavors to the local water. Much of it is very sweet and pure.

However, there are areas where there are higher mineral counts than others, which may give the water a slightly yellow tinge or metallic taste, such as Lisdoonvarna in the northwest part of County Clare. This is a Victorian era spa town. For decades, people have traveled from all over Ireland, the UK and Europe to sample the mineral waters here in the spa treatment, which you can still partake today. The water here is high in iron and magnesium, which leave the skin glowing and soft after a good soak. The high mineral content means the water is hard. The harder the water the more minerals cling to the skin and hair. Using a hair rinse or conditioner will make brushing your hair easier after bathing.

In the cities you may get a slight taste of chlorine from treated water, but in the country you'll find water in it's natural state. Those accommodations on well water will have especially sweet water.

Never drink from rivers and streams or other natural bodies of water, as they can be polluted with anything from animal waste to human pollution, even if it's not evident. Well water is filtered through porous stone to filter out impurities, and in most cases, there are additional man made filtration systems in place as well.

While there are the very rare situations of accidental pollution, Ireland's public water is usually perfectly safe to drink. Where accidental pollution occurs, there is plenty of notice of the event to make alterations to your itinerary.