The test kit should be ...

The test kit should be simple. Pool kits are easy to use and can come up with surprising results. Our students discovered fault related springs based on pH and alkalinity. The project was to detect pollution sources.  Another local high school, using pool test kits, found a chlorine leak at a municipal station. 

BTW, in 1969 the search for a phosphate source to test a new AA machine led to the nationwide reduction of phosphates in laundry detergents.