I just bought a house and while I was doing some yard work in the front, I noticed a partially uncovered plastic lid on a plastic pipe. It had a whole bunch of toilet paper around it but I never noticed it as it was under a large bush. At first, I didn't know what it was, so I just placed the cap back on. Everyday, I came out to check it and the cap was still on. After a couple of months, I noticed again, the cap ejected. This time, it had a whole bunch of water close to the top of this pipe.
What causes this pipe lid to eject? Is water suppose to go up to the cap (top of the pipe)?
The only thing I noticed lately was that the toilet bowl water was low. After a couple of flushes, it came back to level.
Any help and advice is appreciated.