Dear Mr. Nogueira da Silva. ...

Dear Mr. Nogueira da Silva.

Basically you should request them how much water do the expect to harvest, where are they going to keep it, in which uses are they going to employ the water treatment, and which kind of treatment(s) are they going to employ with the water before using it.  And If by any chance they ask you that you should give them the regulations, you can 'put the ball in their roof' showing them that you are open to see how much do they care about the environment and which is their aim. You want to see their degree of compromise they have taking care with the environment. Once they submit you their proposal, we can analyze the parameters they provide you.

Regards to @ll.