I use cloth wipes. The pea pods ones are good (even though pea pod nappies aren't).

I just have a pile of wipes and a spray bottle with water by the change table. I think I have 10 wipes and I wash every second day.

I use flushable liners and find them excellent. You can wash and reuse them if they are just wet. I just chuck them in the wash with the rest of the nappies.

Also, it is the norm for all water that goes down drains in houses to go to sewer. Someone mentioned about septic tanks and using the laundry sink... So whether you flush down the toilet or wash down the laundry sink, kitchen sink, shower, etc, it will end up in the sewer. The issues I see are introducing germs and causing clogs. But rinsing newborn poo down the laundry sink should be fine.