Vacu-flush water supply: Why vacuum hose?

[Mirage35]

The fresh water connection hose to my Vacu-flush has developed a pinhole leak. Temporary repair with self-fusing tape is holding but I will want to replace the hose.

The existing hose is vacuum rated, similar to the extraction hoses (but smaller, of course) that connect to the vacuum generator and holding tank. I don't understand why this would be necessary - it's just connected to the pressurized fresh water system, not the vacuum system.

Does anyone know why I can't replace this with a normal water hose of appropriate diameter?

[Montanan]

Albeit not knowing the mechanism of producing the vacuum, I will propose that the pressurized water is being used to power an eductor [a.k.a. a jet pump] to induce a vacuum to assist with the flushing action.

The issue with vacuum is that it literally sucks and one does not want anything to blow that.

[Mirage35]

It's actually connected by a tee joint to another line that goes to the water heater. So I think I'm answering my own question - if the two other hoses connected to the tee are okay with it then there's no reason why this one shouldn't be.

Vacu-flush toilets have a vacuum generator between the toilet and the holding tank, and those connections need vacuum rated hose.

[peghall]

All hoses in any sanitation system should always be marine sanitation hose. Plain ol' clear vinyl water hose will not last very long...You can use flexible PVC #148 (the cheapest) for this job.



--Peggie

[Windpilot]

I've had my 2 VF systems for 12 years now.
The fresh water "pressurized" line is not part of the vacuum system itself. It's basically on/off to flush and add water. There's also a vacuum breaker at the back of the head so no way it could ever suck anything back into the freshwater line.
Use normal/same hose.

[Mirage35]

Ah, the expert has spoken. That looks like a stock item at my nearest chandlery so it will be easy to give it a try - and cheap enough to keep a spare on hand.