Cheyne, The first step if ...

Cheyne, The first step if you haven't already done so is map the water system: all pipes, valves, points of use, cross-connections and meters. Then identify the volume used at each major point and ensure that you properly understand where all the water is used. Unless its a new factory or someone has looked at it before, you're likely to have inherited a system with leaks, cross-connections, and odd uses that nobody knew about. Fix that first, and add additional meters if necessary so you can MONITOR what is being used in each part of the factory and prevent wastage.

Also have you considered alternative water sources such as boreholes or rainwater harvesting instead of using potable water for some applications?

After doing the REDUCE bit, look at methods to REUSE the water without treatment. Collect rinse water and use it for washing, for example.

Only after looking at all the reuse opportunities should you move to the final stage of RECYCLING water, with appropriate treatment. Be careful because you'll get all sorts of salesmen trying to sell you snake oil, most of whom should be banned from this forum. Look at what is in each "waste" stream and what you'd need to do to enable you to reuse it elsewhere, and the cost/reliability issues with doing so. Speak to the experts, as others have suggested.

Good luck, and stick to the principles: Reduce, Reuse, then Recycle.