Best wishes for the best court surfacing season ever. An important work habit that all surfacing applicators must develop is as follows. The wash water is not hazardous waste, but when it is done by a contractor, it is considered industrial waste. One never knows who is watching when some worker lets wash water run off onto the ground or down a catch basin into a stream. It is a frightening experience when all of the enforcement and clean-up folks appear.
Worst case is that the penalties can be staggering.
Save the water and use it up in the next mix of Novasurface or some other first coat.