I have noticed a large number of RVers who pull into a campground and immediately hook up their sewer line and open the black dump valve and leave it open for weeks at a time. I have been RVing for 15 years and when I bought my first rig, I was told to wait until my black tank was 2/3 full before dumping. Leaving the dump valve open lets the water and liquid go out, but the solid waste tends to build up in the tank. I don't need to describe the potential problems. Plus using the gray tank AFTER dumping the black tank helps to flush out the sewer line. Has the logic for this changed over the years? You can POSSIBLY leave the gray tank open (it is just soapy water usually) but NEVER, NEVER leave the black tank open. Is that still a good rule to follow?Thanks in advance.

I've never understood this one either.I don't hook up the sewer line until we're ready to dump. This way I only handle it once.

Hasn't changed for me. I wait till the black tank is almost full or we are breaking camp before I will empty it. Gray tank is different. If it's just my wife and I then I might not even hook up the hose until it's time to dump as a courtesy to those camped next to us. I will leave the gray tank open if there lots of us because there might be six or more showers a day. I will close the gray tank the day before we break camp to ensure there is plenty in there to flush out the hose after the black tank dump. I also have a black tank sani-flush to make sure things are cleaned out.

Same here... You would think they would like to have a full waste tank to help clean out the lines when flushing the black tank...In our smaller OFF-ROAD POPUP we don't have any of those worries haha... Only has one fresh water tank...This is my sink water draining operations..When one of 7 gallon container gets full I will use my portable folding two wheeled cart to haul it off and bring back some fresh water in 5-gallon water jeri-can haha...Roy Ken

Not only won't I open the valve but will not even hook up the sewer line until I need to dump. I don't want any nasty crawly things from the septic system getting into my hoses. And if you leave the valve open they will get into your RV. If I will need to dump more than once I will leave the hose connected to the RV valve but will cap off the other end.

Thanks Mobilebasset. You have pointed out a good reason to not even leave the gray tank open. I had not thought about that.

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Old-Biscuit
Explorer III
Aug 07, 2016
How do you know it's their black tank drain valve vs grey tank drain valve ?
bukhrn
Explorer III
Aug 07, 2016
I don't know where you've seen it all those times, I've never seen it, but then I don't watch EVERONE hook up.
I never open the valve till I'm ready to dump.
RetiredNavy
Explorer
Aug 07, 2016
Thanks Mobilebasset. You have pointed out a good reason to not even leave the gray tank open. I had not thought about that.
MobileBasset
Explorer
Aug 07, 2016
Not only won't I open the valve but will not even hook up the sewer line until I need to dump. I don't want any nasty crawly things from the septic system getting into my hoses. And if you leave the valve open they will get into your RV. If I will need to dump more than once I will leave the hose connected to the RV valve but will cap off the other end.
RoyB
Explorer II
Aug 07, 2016
Same here... You would think they would like to have a full waste tank to help clean out the lines when flushing the black tank...

In our smaller OFF-ROAD POPUP we don't have any of those worries haha... Only has one fresh water tank...

This is my sink water draining operations..

When one of 7 gallon container gets full I will use my portable folding two wheeled cart to haul it off and bring back some fresh water in 5-gallon water jeri-can haha...

Roy Ken
azdryheat
Explorer
Aug 07, 2016
Hasn't changed for me. I wait till the black tank is almost full or we are breaking camp before I will empty it. Gray tank is different.

If it's just my wife and I then I might not even hook up the hose until it's time to dump as a courtesy to those camped next to us. I will leave the gray tank open if there lots of us because there might be six or more showers a day. I will close the gray tank the day before we break camp to ensure there is plenty in there to flush out the hose after the black tank dump. I also have a black tank sani-flush to make sure things are cleaned out.
ScottG
Nomad
Aug 07, 2016
I've never understood this one either.
I don't hook up the sewer line until we're ready to dump. This way I only handle it once.

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