John's suggestion about the water pump is worth noting. Mine was leaking, but I didn't notice until it really started leaking when I got the the Algarve. I had a new one fitted and the old guy who did it rebuilt the old one as a spare.
As for the grey water, yes everything gives down to the sump. The automatic pump does not extend as far down into the sump as the manual pump. So every few days pump the last dregs out by hand after the automatic pump has stopped. This gets rid of a lot of the worst stuff that sinks to the bottom. The build up of soap residue does create a nasty mess that sticks to the sides of the sump and the grey pipe that guides the float switch. I was told to put a dishwasher tablet in the sump once a week to help disperse this. I now put in some of the liquid you put in the dishwasher reservoir to stop the soap sheen on glass. I leave this in overnight so it doesn't get pumped out too soon.
Admiral Bill (ex Be Be) said something about clamping an old sock over the sink outlet pipe in the sump as a sieve, and replacing it as necessary. I will give that a go when I get back to the boat, because cleaning the bilge is only just a bit nicer than taking the toilet pipes apart!
Look after the bilge, because that is where the copper grounding strap goes down to attach to a keel bolt to connect the stub keel to the rudder zincs. They do rot through eventually, probably related to the composition of the mixture that goes through the bilge. There are posts on the forum related to replacing this. But you do have to empty the bilge totally to check the copper strap integrity. If you don't know when it was last checked or replaced, keep that one near the top of the to do list.
However, don't get too hung up over all these comments. Get out and sail the boat first. There are plenty rainy days to check all this stuff.
Ocean Hobo SN96