Nope. American milk is pasteurized to a much higher temp. It lasts way longer. Irish goes off in days, US milk will last a month in the fridge.
The extra pasteurization effects the taste and flavor.
High-Temperature, Short-Time (HSTS) Pasteurization appears to be the standard in both Ireland [1] and the US [2] -- 71.7°C / 161°F for 15 seconds.
And I can tell you from personal experience that US milk goes bad in days as well, and has for decades. I don't know where you're getting the idea that it lasts a month in the fridge.
There are real differences in some foods between the US and Europe, e.g. American eggs are washed while European ones aren't. But fresh milk from the supermarket appears to be very much identical.
https://www.tesco.ie/groceries/en-IE/products/250005606
It's essentially identical to whole milk in the US. Nutritionally, compositionally, and flavor-wise.
I really can't imagine what you're talking about "tasting like water" unless you switched to skim milk or 2% in the US without realizing it?