My Gas bill was ¥17,000 for last month

So I just checked my Gas bill and it was ¥17,000 and I use stove. Can anyone tell me what might be the reason for it? I use heating feature on the tap to wash utensils and shower with warm water too. What could change so dramatically cuz in September and October it was hardly more than ¥5,000 but this time it’s more than 3 times of it. Any suggestions on how I can save on it?