Very guttural - kind of like in French

Unlike other languages, you kinda do it at the back of your throat, so we don't really use our tongues. It's hard to explain... Have you ever tried gargling just without water? It's a bit like that I guess.

Actually, there are two different sounds. It depends on the position of 'r' in the word. When it is not at the end of the word, then it is what Sarah had explained very well with the gurgling sound without water. When it is at the end of a word, then it is a short 'a' sound. The -er in 'water' in British English and in the German 'Wasser' are very similar.

Like an "ah" I think.