Hello,
I answerd the food question in the food tread.
The water I use is rainwater and I got the same good parameter as Bernd.
A friend of me asked me if it is possible to use water which flowed oder an bitumen-top.
I think it is ok, but there are gases and carbonhydrates which may come out in the summer when it´s hot. I used water which fload over bitumen but only when there was enouth rain to exchange me tanks (4x 250l). There should be nothing left.
But what do you think? Are carbonhydrates or other bitumen parts dangerous?