87 Sea Ray SundancerAfter putting my boat in the water this year I filled the water tank and ran the sinks to flush. However I noticed after doing so I had standing water in the bottom step for the cabin below the driver’s bench above. I opened the little door under the cabin and there was water. I used a shop vac and sucked out the water. I filled the tank again and had the same problem. I don’t know if I didn’t turn on a valve or something that lets the water into the holding tank or something like that. I bought the boat last summer and didn’t have this problem. The mechanic at the marina winterized the boat, but I don’t know what he may he have turned on or off. Sorry for my ignorance. I’m learning there’s a big learning curve with boating.