The use of Brita filters has been discussed on a number occassions, you can try a search using the function at the top of the page.
Essentially the Brita filters have a pretty limited capacity to remove calcium and other scale causing chemicals.* Depending on the amount of ions in your tap/source water this capacity could be lost after only a few litres.* If you live in Melbourne which generally has very soft water, it may be fine.
The Sunbeam filters can be recharged, again you can search for the method to do this.
I have filtration system connected to my kitchen sink. After the filters are around 3 months old I tend to check the water with hardness test strips which are quite cheap, especially if bought in bulk. I guess in theory you could test the water coming out of the group on your Sunbeam for hardess.