The Times Science section reports on a novel water testing strip developed by scientists at McMaster University in Canada. Instead of having to a fancy analytical assay to see if the water is good, you simply expose the lateral flow test which activates what is essentially a water diagnostic.
The New York Times:
...But scientists at McMaster University in Hamilton, Ontario, are reporting the development of a simple paper sensor — a “laboratory on a strip” — that can be dunked in a sample and give a reading a short time later, like a litmus test.
The sensor, developed by John D. Brennan and colleagues, makes use of the fact that organophosphate pesticides like diazinon inhibit the action of acetylcholinesterase, an enzyme involved in nervous system function.
More at the Journal of Analytical Chemistry