As part of a recent American Chemical Society meeting, meanwhile, high school students from Maryland presented their solution to prevent lead contamination.
Their 3D-printed 7.5cm tall filter is made from biodegradable plastic and can be easily attached to the faucet.
It contains a cartridge filled with a mix of calcium phosphate and potassium iodide powder.
The former binds the lead, which sinks through a nylon screen and is then trapped at the base of the unit.
If binding capacity is reached, the potassium iodide reacts with the excess lead, colouring the water yellow. A sign to change the filter.
For legionella, of course, there’s a PCR test.