2 Ideas for concept map

I have been around the net tonight looking at water purification articles, and one of the topics that I think could go on our concept map is "homeade water purification technologies".
This includes ideas such as:
Boiling water to remove pathogens (a good demonstration that teachers and elder students can do in the classroom)
Chemical treatment: the use of iodine or chlorine in water to remove bacteria and other harmful organisms
Chlorine treatment, many cities use a form of chlorine treatment in their tap water systems
Filtration systems, i.e. charcoal filters for campers (I have used charcoal filters in the past on camping trips, and have a basic understanding of how they work), brita filters, pur filters for the home (many families have these types of filters that are part of a pitcher, a refrigerator, or come as an attachment to a sink faucet).

Another idea for the concept map to go along this line is:
We use water every day to drink, cook, and bathe. How is that water recycled in our cities and towns water systems.
so the concept for this part is "recycled water" or reclaimed water
This process is interesting because it takes the water we use everyday, treats it in much the same way for home use then releases the water back into the aquifer to rejoin the water cycle.
Now this process leads to the question is the water safe to drink or not? Well not exactly some impurities can remain in the recycled water but they cam be filters out by many of the standard filters and other systems that are put into place by cities and towns.
Lastly students interested in this topic can look at the concept of recycling water aboard the international space station,and learn how the astronauts can recycle their urine into actual drinkable water.