Obviously criticizing  Israel is not antisemitism.  But where it could be antisemitism is when only Israel is singled out.  I don't need to list out the number of countries that have issues with various minority, and some of those go far as to apply ethnic cleansing or genocide or religious legal discrimination, none of which apply here.

Arab Palestinians in the West Bank are not Israeli citizens (fact).  Gaza is in a state of war with Israel (fact) so Israel has no obligation to open its border, even though it does for humanitarian activities (fact), while Egypt has locked its border with Gaza (fact), yet Waters accuses only Israel of keeping them in a prison.  Jews do not have many rights in most Arab nations, for example.

Arab Israelis have full rights under the law as citizens.  Like all countries, there is social discrimination.

Waters singles out Israel despite all that.  Why picking out Israel?  Oh, it happens to be the "Jewish state".