It really depends on how much the charges will be.
As Diablo has said, wort chilling would be the main wastage culprit. I must actually see how much water I use when chilling the wort on my next brew day.
I would say the main affect the charges will have will be to make people think twice about leaving a tap running and wasting unnecessary amounts of water.
Be interesting to see how this initiative is going to be rolled out and managed, and also how easy it will be to bypass the actual meter if one was inclined to do so, not that I'm suggesting that for one minute.