I am pretty old now and I do not think I have ever heard it called a wash bowl. If anything it's called a hand washing sink, or just a sink.

That's a picture of a "sink." In the United States, it's a "sink," period. (Checking:) Well, my wife says something a little different. She that, to her, it is a "sink" if it has running water, and it is only a "wash basin" or "wash bowl" if it does not. My wife adds that she thinks plumbing catalogs sometimes use different names than we use in real life, and she thinks it's possible that the people who manufacture them call them "wash basins" or "wash bowls." I had been going to say that "wash basin" and "wash bowl" had died out, and her take is that it is not the words, but the things themselves, that have faded. In any case, "washbowl" and "wash basin" date from the days when a bedroom contained a very big ceramic pitcher of water, and a ceramic bowl or basin to pour it in, for washing hands and face. (And, of course, a "chamber pot," discreetly hidden somewhere). When I was a kid in the 1950s, my parents still called refrigerators as "iceboxes," and it is possible that in that era some people might have called bathroom sinks "wash basins" or "wash bowls." I probably wouldn't notice if someone used those words now, because they're in my passive vocabulary and they don't sound strange to me unless I think about them.

I think everyone would understand it if someone used "washbowl". "Sink" is what i hear used the most. Sometimes "basin".

I think you can safely forget that one. Even 'washbasin' I rarely hear, I'd just call the item in the photo a 'sink.'

P.S. It's always interesting to try Google Images. A Google Images search suggests that just possibly plumbing manufacturers use "washbowl" for a specific style of sink