Originally Posted by GaryHLucas
I hope you realize that you now have what may be drinking water connected to a sewer line. On land that is illegal unless you have backflow prevention device. A house toilet does that by using a gravity tank. It would be bad to make someone sick on your boat.
ABSOLUTELY CORRECT ---- UNLAWFUL DANGEROUS POTABLE WATER CONNECTION TO 'SEWER SYSTEM'
Backflow preventers are 'iffy' to prevent retrograde bio-contamination from a sewerage system. You need an 'air gap' - similar to what you find in a toilet tank to prevent retrograde bio-contamination. In this application a backflow preventer MUST be certified
(via 'sanitary codes' -- NSF or FDA, etc.) vs. retrograde bio-contamination.