I’m not in the Med, but If I were I would buy a large plastic water container, temporarily replace the outlet pipe on the bilge pump into the container to empty where you can.
Means being frugal with water at anchor. If this issue becomes more widespread I’d put a diverted valve on the outlet hose into a permanent tank.
From our Amel perspective this is a whole lot easier than a conventional boat with multiple seacock drains to sinks and showers.
Ocean Hobo (Wales)