OK, thanks to our next door neighbour Craig (http://www.sandrineandcraig.com/) for pointing out that it's actually for sewerage and river management fees! =))
Surprisingly, we've received a water bill... not for our current house.. but for the one we're building! Hmmmm.. We built our current home less than 4 years ago but never receive a single bill for water at all. I raised it with EB and was told that this forms part of our construction costs.
Has anyone experienced the same with EB or with the other builders too? Is this the pratice these days?