Hi, We have 2 Toto drakes in our home. They were both professionally installed about one year ago. In our master bath, I noticed that occasionally I can hear the Toto refilling and water running through the pipes, like it does when it refills its tank, but for a shorter amount of time. This happens maybe every three or four hours even if nobody had used it recently. On some occasions, the water trickling noise will come on even when a person is sitting on the toilet before they have flushed. The other Toto seems to be working fine, so the problem just occurs on one bathroom. Can anyone give me advice on what the problem might be? thanks for your help!