This Friday we picked up our new 2024 Inagine 2800BH. We love it. I don’t, however love this issue. We left the dealership and arrived at the our campsite for the first night and set up everything but the sewer. We used our shower x3, washed dishes, brushed our teeth etc. In other words, we added waste water to all sinks/tanks. The next morning (Saturday) I went to connect my sewer hose and removed the sewer cap only to have a rush of water come out onto me. Not fun. Also included in this were 2 or 3 small bits of plastic about the size of a quarter. Aside from gross, I assumed it was maybe water and antifreeze from manufacturing. We left the campsite and travelled home. On arrival I again opened the sewer cap and more water came out. At this point the tanks should have been empty except there was only 5 gallons of fresh water that I added to my black tank after dumping the tanks at the campsite along with a tank treatment. I don’t know if it was residual water from the galley or the BT. Looking for some suggestions. Thank you.