Electrolyte challenge, why dip in tap water

[agbeckman]

In the example experiment for the electrolyte challenge the conductance sensor is dipped in tap water followed by distilled water in between each sports drink that is being tested. We understand using tap water as one of your tests as it is a conductor. But, what is the purpose of first dipping it in the tap water rather than just using the distilled water to rinse?

[bfinio]

Hi - this is just a multi-step rinse process, using tap water first to avoid contaminating the bowl of distilled water. That step is probably not critical to the experiment, you'd have to test but it will likely still work OK if you only rinse in the distilled water. After performing a lot of tests you may need fresh bowls of rinse water if you notice your results starting to drift.