# Connections From Black Tank Flush



## MacTeam (Jul 27, 2008)

OK, I was doing the simple mod of changing the door under the sink from a useless laundry hamper to a traditional side opening door. While in there I saw the hose coming from the factory installed black tank flush. (OB 295RE). The hose comes in and goes up almost to the bottom of the sink. There it is connected with a black "thingy" to another hose that runs back down to the black tank.
Does anyone know why it is configured that way? Why not run the hose straight to the black tank? What is the black "thingy" for?
Inquiring minds want to know... thanks.


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## Nathan (Jan 2, 2007)

It's a vaccum breaker. That way, if for some reason a vaccum was pulled on the hose, you wouldn't be able to suck the black tank back into the feed hose.


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## MacTeam (Jul 27, 2008)

Well who knew....
(Though I can't imagine anyone trying to start a syphon from the black tank cleaner! Yuck!)









Thanks.


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## Nathan (Jan 2, 2007)

Not saying anyone would do it intentionally.....


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## john7349 (Jan 13, 2008)

Nathan said:


> It's a vaccum breaker. That way, if for some reason a vaccum was pulled on the hose, you wouldn't be able to suck the black tank back into the feed hose.


Sure hope Gilligan remembers to install these.


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## outback loft (Sep 22, 2008)

Well people have done it around here. That is why all our water spigots now have anti-backflow valves on them. Don't ask me how these people manage to do it, but now the campgrounds had to install the valves for heath reasons, although I don't think anyone is going to get water to backflow into a spigot with water pressure anywhere around 70-100 psi.


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## Nathan (Jan 2, 2007)

Typically the water lines at dumps stations all have vaccum breaks. Its also required in our area that Sprinkler systems have them installed. If you ever lose water pressure completly, it could rather easily suck water back up into the lines.


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