Hello Anova Community! This is Jeff Wu (Senior Engineer @ Anova) - I wanted to speak to some of the corrosion questions that have been asked recently. There is absolutely no issue with the water sensor and what everyone is seeing is normal. The water sensor will discolor and people will see build up under normal usage but this is completely expected (just to reiterate again). 1) Question: Why does the probe turn brown or black? Answer: During manufacturing (forging, cutting, and polishing), impurities in the steel and residuals from cutting and polishing end up imbedded into probe. During the first few weeks (depending on usage) the impurities and residuals leach out (yes this is normal). This process turns the probe brown or black. After the break in period, this process will eventually stop and the probe will last forever. 2) Question: Why is there build up on the probe? Answer: This is a normal build up of mineral deposits mostly from tap water. Build up can be brown, black or even green depending on your water pipes and water source (if you drill your own well or use a water utility). Please let us know if you have any additional questions about your systems. Your feedback is incredibly valuable. Thanks!