I have to do a presentation for biology on 'recycling & treatment of water'

I am having difficulty with what information is important.

The presentation is only supposed to last 2-3 minutes (which is part of the difficulty as I only have a short amount of time)

Any tips/advice
Any suggestions for what to choose to say
Any help at all - Thanks!

3 answers

Important issues:
The treated water has to be quality water, ready to drink.
The sewage has to have trace amounts removed: heavy metals, biological, etc.
The sewage treatment plant has to operate 24/7, otherwise, a disaster for folks using the sewage system.
Treatment has to be environmentally friendly (ie, no chems added that make the water not treatable downstream)
Finally, certain things that cannot be treated have to be banned (ie the Shampoo with Lindane (Broken Link Removed) from sale
For recycling, you can also look at greywater recycling, for example:
http://en.wikipedia.org/wiki/Greywater
although it is only a developing resource in the Western world.
if you are smart enough, you should know that there are a a lot of facts on google or wikipedia