The last few days the toilets in the house (2 toilets) are making a gurgling noise. When I go and look, I can see the water is standing very low. When I then flush the toilet, the water either keeps rising (not going down the pipes) or flushes normally. And then there's about a 50/50 chance of it to start gurgle again.
We've tried unclogging it with a plunger, but it does not help. So I'm suspecting it has something to do with the septic tank.
What should I try to fix this?
EDIT: I should also note that one toilet is on a floor higher then the other.