Easiest way: put a little weight on the Part which close the valve/plunger.
A bit harder: try to clean the bottom/o-ring of the valve/plunger.
Or replace the o-ring Seal. I had this problem once, replacing the ring solved it. There was a continuous flow of water that drained the reservoir and thus leading to the influx of water every hour or so
Easiest way: put a little weight on the Part which close the valve/plunger.
A bit harder: try to clean the bottom/o-ring of the valve/plunger.
Or replace the o-ring Seal. I had this problem once, replacing the ring solved it. There was a continuous flow of water that drained the reservoir and thus leading to the influx of water every hour or so