Looks like a Willie Wagtail to me (Rhipidura leucophrys). Very cheery birds to have around. Got a lot of spunk, too. They'll fearlessly chase birds twenty times their size.
Oh Mirek, thanks for posting that! I love Willy Wagtails! (They are a type of fantail).
BogongBreeze is right- they are not too shy, and like to `investigate' you when you're in their territory. If you do something `wrong' they will tell you off, giggle Theres nothing like being told off by a small bird
We also have a small salt water in-ground pool, which attracts Kookaburras, sacred kingfishers, and very rarely the willy wagtails and pee-wees (Mud larks). But I must confess that it has become a frog pond over the last year, since the water restrictions prevent us from using hoses to maintain it or clean the filters.
It must be such a treat seeing goannas swim in your pool! We don't have any in our area.
Giggle- sorry I misunderstood. My folks live up North and the Goannas swim in their pool. But I think they affect the water and it becomes a chore to keep the chemical balance right.
I love your picture of the Goanna! Its such a buzz encountering a huge one! i haven't seen one in a couple of years.