According to our water bill I use as much water a day as an extra person living with us. This equates to around the 150 litre mark which covers 5-10 litre water changes on my smaller, non-cycled tanks.
Most of my bigger tanks are cycled so they only get done once a week.
Our electricity bill was $600 last quarter, which comes down to around $50 a week (I pay this weekly to my mum). However, I am building two barracks to house 20 of my males so that should cut down on costs hopefully.
Luckily this is my only serious hobby or I'd be broke and living on our front lawn in a box.