In the instructions it says you can do a low level disinfecting every other treatment day with vinegar after first cleaning it as usual in soapy water. They say 1 part vinegar to 3 parts hot water for 1 hour. When you did your soak before boiling did you use that amount of vinegar to water? And do you normally use vinegar as they instruct? I have never used vinegar but sounds like I should start. Wonder if using it as they instruct some days and then boiling other days would do the trick to keep the cups working well.