I've been using iButtons for 4 years to measure water temperature which allows me to determine ponding depth through time. The batch that I bought 4 years ago was essentially waterproof and their failure rate ran about 5% per year regardless if they were immersed or not. This seemed to mirror the experience of other users. I bought a new batch last December and just determined that 66% of the immersed the new iButtons failed. I haven't opened any of them up but I assume that the failures were caused by leakage. To me this indicates that the manufacturing process has changed. The supplier responded to my inquiry simply that they are not warranted to be water proof. All I can say is that the change means that we have lost a very useful tool.
John Gerlach
