While the provision of safe drinking water in impoverished countries is of vital importance, people often lack the facilities necessary to test the water for pollutants. To help solve that problem, a team of scientists has developed a system that uses a smartphone camera to check up on tiny aquatic organisms.

Coming from researchers at the Singapore University of Technology and Design, the setup is designed to analyze untreated water samples from lakes and rivers right on the spot, within just a few minutes.

The team came up with the system after zeroing in on paramecia, single-celled organisms that are abundant in bodies of water across the world. The researchers first noted the average swimming speed of the organisms in unpolluted water, and then observed how much the speed varied as different concentrations of toxins such as heavy metals and antibiotics were introduced.

Next, the scientists measured the swimming speed of the microorganism in water samples using a simple microscope attachment on a phone camera, along with object tracking algorithms. The team then discovered that they could accurately identify how polluted the water was, just by observing how much slower than normal the paramecia swam.

They found, for instance, that even when polluting elements were present in concentrations considered to be half of what’s safe for drinking, the swimming speed of the paramecia decreased by half, reports New Atlas.

“Taking a sample of water and measuring the speed of paramecia can therefore be used as a straightforward method to assess the drinkability of water without the need for specialized equipment or chemicals,” says Fernandez. “Usually, you would need a different test for each pollutant, but paramecia swimming is a global measurement.”

Source study: Scientific Reports — Measurements of the swimming speeds of motile microorganisms using object tracking and their correlation with water pollution and rheology levels