For a few months now we’ve been working to build an affordable turbidity meter that’s accurate enough for basic water quality testing. Our first prototype was Bluetooth-enabled, used a tethered Android smartphone to display data, and involved an expensive, high-precision 3D-printing process to make the chamber to hold the water sample.
After getting feedback on the device from some non-profit and charity agencies focused on rural, low-cost water testing, we’ve begun work on reducing costs even further and developing a first-stage model that is suitable for assessing the chlorine demand of untreated water. In technical terms, this means it will have an accuracy of +/- 1 NTU on a range of 0-20 NTU, and +/- 5% in the range of 20-50 NTU. We’ve switched our optical sensor setup, and are investigating the even cheaper sensor options. You can see our current sensor of choice (the TAOS TSL230R), both by itself and snapped in to a new Makerbot-printed sample holder in the photos below! We’ve replaced the Bluetooth unit (and Android tethering) with a simple Nokia 5110 LCD monitor — which provides basic text and graphical display for only $10. So, we’re able to assemble the complete working insides of the new turbidimeter for less than the cost of the sample holder in the previous model. The only remaining piece is the case, which we will be 3D-printing with a Makerbot this week.
This weekend WASH For All members Chris Kelley and Alex Krolick will conduct an intensive round of testing in Ithaca, NY. Check back in with us next Monday (April 8th) for the results!