My toilet is two years old–small capacity flush (1.8 gal). After a complete flush, the tank refills; then after about one or two minutes, it makes a “mini-flush” all by itself! At first this mini-flush only happened once after each flush, now it is happening two or three times after each flush. Is it the flapper or is it the diaphram? Thanks.
It more than likely is the flapper.Check the flapper and the place where it rest when down and check if any build up is sitting there.Also flapper may need replaced even if only 2 yrs. old.Depends on water.Also check the little hose that goes into the overflow and make sure it is not in to far.It shouldn’t be below water level when toilet is full as it has been known to syphon back and creat situations such as this.I hope this helps I know toilets can be very frustrating at times.