A lot of your water-related questions are perhaps best addressed by looking at the use of water for agricultural, urban, or energy related purposes. So be sure to check out those pages if you are interested in a water-related project.
Desalination is one growing solution to the world’s problem of limited freshwater supply. Your case study might already rely on this technology to meet some of its water demands. An interesting comparative LCA might be conducted comparing the impact of various desalination technologies and potentially examining any links to energy and agriculture in a region.
Comparative LCAs for desalination involve creating two full LCAs. A full LCA requires you to closely examine a specific project and find data related to it, examining all inputs and outputs. Extrapolation of data from other areas may be needed if data are difficult to find. The functional unit for a desalination LCA will be any unit of volume of water (m3, litre, gallon, etc.). Different desalination methods to examine include reverse osmosis and multi-stage flash distillation.
The following papers provide a good starting point for these issues:
– Attari, S. Z. (2014). Perceptions of water use. Proceedings of the National Academy of Sciences, 111(14), 5129-5134.