Salt Test Kit

[chem geek]

Taylor kit K-1766 will test for salt -- it tests for chloride, but reports back as one drop for each 200 ppm salt (NaCl). It's $20.75 which isn't cheap, but you probably won't be testing that often so won't be using up the reagents very quickly. It's mostly expensive due to the silver nitrate reagent (and silver isn't cheap these days).