Hi I installed 400a a couple of year ago, you can hear a running noise after the toilet fill up. But no water is coming out... is there an internal leak.
My water bill was higher than normal for winter time.

Sounds like your flapper is leaking. Also check your chain and handle that engage the flapper.

Toilet Bowl Not Filling | Toilet Not Flushing | Toilet Flush Valve

Let me know what you find.

Also, make sure your house water pressure is set to 55 PSI. That is the suggested operating pressure for all plumbing fixtures in your house.

Milo

I agree re the flapper. To test this add a few drops of food dyr to the tank. Check the bowl in an hour to see if the bowel now has colored water too. If it is a bad flapper you can replace for a few dollars but check the rim the flapper rests on, be sure there are no nicks or bumps. If there are nick the whole flush valve needs to be replaced but not the fill valve.