Backflow Valve

[IDguy]

Since I’m pretty sure the blank tank flush enters the tank above the bottom and the drain is open when flushing I don’t see backflow as a concern. All dump stations I’ve visited have separate non potable water hose for black tank flush.

Not something I worry about. So far with 50 years of RVs never an issue.

[CHRIS1u]

If the hose used for flushing is only connected when used for flushing (ie, with positive flow into the rv) there can't be backflow. Backflow is a problem when a connection (hose OR pipe) is idle while connected to an active system that may create a vacuum, drawing undesirable fluid from the inactive hose (basically, Bernoulli's principle).



I think the big issues are these: 1. Dumping and flushing is an ugly process, and I'd prefer my fresh water hose keep its distance. 2. The fresh water hose should be made of "safe" material...in particular, no lead content. An ordinary garden hose is considered unsafe (although I have consumed a lot of water from a lot of garden hoses over my 78 years).