I'm a student, and we've been tasked to create an arduino project for a competition. I wanted to create something that detects certain metal pollutants in water that make it unsafe to consume. However, I still haven't found if there are sensors for this.
Which "metal pollutants" do you want to detect?
Quite surely. How easy and expensive, depends on what you need to detect. If you are looking for a $10 sensor for "unsafe drinking water metals", you are out of luck.
Sorry that is not a simple test.
To determine if drinking water has unsafe levels of metals, you should conduct a water quality test through a certified laboratory. Common metals to test for include lead, arsenic, cadmium, and copper, as these can pose health risks if present above certain limits set by the EPA.
And other levels set by states.
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There’s no single simple sensor that can reliably detect full drinking water quality, but for basic checks, a tds (total dissolved solids) meter is often used. It measures conductivity to estimate the amount of dissolved ions, which gives a rough idea of purity. However, it doesn’t detect bacteria, heavy metals, or chemical contaminants—so it can’t guarantee water is safe to drink.
To detect heavy metals in water, you typically need chemical analysis methods like atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, or specialized test kits with colorimetric reagents. These kits can indicate the presence of specific metals like lead, mercury, or arsenic, but they’re usually limited in scope and precision compared to lab methods.
In any case it’s not a simple sensor hanging in the water and telling you « it’s all fine ».
You probably need to find another idea for your project.
Long a go in a discussion we "invented" the sensor that just always returned true.
So in this case it would always say "water is unsafe" as that is the safest advise one can give.
No metal detection but some ideas to detect pollutions.
- build an electronic nose, that sniffs the water for certain gasses.
- build a color detector, shine light in different colors through the water to look for its opaqueness in different wavelengths including IR and UV. Water should be transparent at all wavelengths but not for UV and IR.
- measure the pH of the water? Is in fact a conductivity test as mentioned above.
- Another test is to shine a laser on the water and measure light scattering due to micro particles. (you need very transparent possibly thin test tubes)
- with a laser you might detect a difference if the breaking index of clear water vs polluted water? (don't know if and how much it changes, is a project in itself).
- you can cook the water and measure the weight of the residue. Very slow and time and energy consuming but clear water leaves almost nothing behind.
- you can cook the water and see if the cooking point is 100°C When something is dissolved it changes the cooking point. You need to take the air pressure into account as it affects the cooking point too.
- Same trick now with freezing. If the freezing point is below 0°C there is something is dissolved in the water.
- determine the specific mass of the liquid, water with dissolved stuff is heavier. Might need a serious expensive scale on the on the other hand.
- .... and breath again
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