I flush the toilet and the water is clear/clean, then around an hour later there is dirty water in the bowl.

I have chucked a couple of bucket loads of water down the toilet and it drains away fine, so doesn't appear to be blocked, but the dirty water is still coming back- how/why could this be?

There doesn't appear to be a bad smell.

Thanks for your help.

Is the water in the tank clear?

Is the water in the tank clear?

We don't have a water tank and the cistern is clean.