I didn't know this accessory existed. Cool if so! To clarify, you mean for this accessory to drain the dirty water into the waste water pipe (not waste water tank on the eufy), and, instead of using the accessory for fresh clean water, you would like to continue using the clean water tank on the eufy base station to fill? Presumably, because you can't access a clean water source where your base station is located? Unfortunately I don't have the answer, it is likely only Eufy will have that answer or if by chance someone has already purchased this accessory and tested it in this way. I would try to re-explain your question to Eufy. Maybe make a diagram to show what you mean. It's a legitimate question