You're thinking inside a rather small box here with the Raspberry Pi angle. Usually detecting harmful chemicals dissolved in water involves running some chemica

You're thinking inside a rather small box here with the Raspberry Pi angle. Usually detecting harmful chemicals dissolved in water involves running some chemical reactions that consume their reagents, not just some reusable electronics. There's a reason the kits are like this, instead of an electronic device: http://www.amazon.com/First-Alert-WT1-Drinking-Water/dp/B000FBMAVQ/ http://www.amazon.com/First-Alert-WT1-Drinking-Water/dp/B000...