Tank dumping

I have a TT that has 4 tanks. 1 water tank.  1 black tank. 2 grey tanks. Other than laziness I don't know why the 2 grey tanks are not connected so they can dump together. Guess the factory doesn't care.

I have been keeping the 2 grey tanks open while connected in the RV park. The black stays closed. I have attached a Wye connector so the hoses are all hooked together. When it's time to dump the black tank, I close the 2 greys and open the black to dump. Then I connect the water and flush the tanks. Does this flush all 3 tanks or just the black one?  How long do you flush the tanks with water?

Thanks for your help. Sometimes I feel like I should know these answers but the dealer didn't have time to show me what to do when I bought it in May.

The flush is only for the black tank. Get a clear sewer hose adapter to put on your sewer outlet. After you dump your tank, flush it until the liquid coming out is clear. Then close the outlet and let the flush keep running for a few seconds to add a little extra water to your tank. That will help keep odor down and assist in breaking down the solids.

... then dump gray water to flush out the sewer hoses.

Carin, you should close your grey tanks several days before you plan on dumping your black tank that way after dumping the black tank you use the grey tanks to help flush your hose. We like to use the hose which only cleans the black tank to flush the black tank until the water runs clear. We have a clear elbow on our dump hose. If the water runs clear, the hose should be clean enough to store.

Manufacturers build the TT's as cheap as they can so they may need more grey tank capacity than what they can get into a space so they may put another grey tank in another space or closer to a drain line. Logic doesn't always prevail in the RV industry.

I never thought of separate gates as being a cost saving measure. It allows the owner to control how gray water is collected, and provides a bit of redundancy should one tank or its plumbing get damaged.

In fact, it's probably more expensive to add the second gate than not,

Carin said:

Sometimes I feel like I should know these answers but the dealer didn't have time to show me what to do when I bought it in May.

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You will probably get better answers here from experienced RVers than you would from the dealer!!!  That's why we are here.  Ask any question you have.

I will not answer this as I would just repeat the very good advise above.

I have to wonder... if you have a black tank flush, and you rinse your black tank till only clear water comes through, then whats the point of saving up the dirty stinky gray water to dump after the clear black tank water?

I can see doing it if you dont have a flush system, and Im sure this practice started years ago before many rvs had the flush in them. But I never save up the gray water to dump after the black unless Im boondocking. I always rinse the septic hose out with fresh water before I stow it regardless, so shouldnt really matter should it?

cadee2c said:

I have to wonder... if you have a black tank flush, and you rinse your black tank till only clear water comes through, then whats the point of saving up the dirty stinky gray water to dump after the clear black tank water?

I can see doing it if you dont have a flush system, and Im sure this practice started years ago before many rvs had the flush in them. But I never save up the gray water to dump after the black unless Im boondocking. I always rinse the septic hose out with fresh water before I stow it regardless, so shouldnt really matter should it?

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To flush away anything that might still be in the corrugated sewer hose. The volume of water that is released when the gray tank valve is opened will get rid of anything that might be left in the hose. No need to rise out the sewer hose afterwards.

Also, gray water doesn't become stinky if you leave the valve closed instead of leaving it open. Just like the black tank, it's the solids in the tank that stink. If you collect the gray water and dump it all at once, the solids flow downstream with the liquid.

In my case, I dump my black, then the gray and finally run the flush in the tank till I am sure all the  hose is cleared. There is times I will only dump the grey as I do have a sealable slinky hose but I do like to make sure it is clean as possible. If I need to work on my valve, I will make sure that the tank is clean. Just had to change the black valve.

gwcowgill said:

In my case, I dump my black, then the gray and finally run the flush in the tank till I am sure all the  hose is cleared.

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I know there's more than one way to skin a cat, but that doesn't make any sense to me. Compared to dumping the gray tank, there's only a small trickle of water from the blank tank flush line. Any "stuff" that gets flushed out of the blank tank stands a good chance of getting stuck in the folds of the sewer hose. By dumping and flushing the black tank, then dumping the gray water, you can be pretty sure that everything has been washed away.

I also have two grey tanks.  The front grey tank and black tank are dumped with the same hose with two pull valves.  I like to only dump the black tank when it is at least 75% full.  I like to let the grey tank to be pretty well full before I dump the black tank so I'll have plenty of water to flush out the hose with grey water. 

I first dump the black tank, then close the valve and allow the black tank flush to fill the black tank for a few minutes, then dump it again.  I then close the valve and allow a minute or so of black tank flush water to go into the black tank so there will be 5 gallon or so in the bottom of the tank before we start using it again.  I then turn off the black tank flush.  The last thing i do is dump the grey tank.  The full grey tank will do a really good job of flushing the hose. 

I also like to keep a low spot in the sewer hose that will act as a P trap.  This prevents any drain flies that may be in the RV park sewer system from entering the upper part of the hose and valve.  I've gotten them in my tank a couple times and I'd rather keep them out.  I quit using a sewer hose support many years ago and found out the black tank will drain just fine without it. I keep the grey tank closed all the time and only empty it when its fairly full.

Carin,it seems from your signature that you have a rear kitchen model.  If that is the case, almost all rear kitchen have two grey tanks.

BigLarry said:

I also have two grey tanks.  I first dump the black tank, then close the valve and allow the black tank flush to fill the black tank for a few minutes, then dump it again.  I then close the valve and allow a minute or so of black tank flush water to go into the black tank so there will be 5 gallon or so in the bottom of the tank before we start using it again.  I then turn off the black tank flush.  The last thing i do is dump the grey tank.  The full grey tank will do a really good job of flushing the hose. 

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This is the same process I use but my last step is after disconnecting the hose from the TT and before removing from dump hole I use my nondrinking water hose to do a final rinse of my drain hose to flush for a final time anything that may have been in the grey tank.
Joe

Thank you for all the great answers and replays!!!!

Have another problem - I'll start a new thread though.

Thanks again!!!!

Our new, 33.5' Heartland Trail Runner 27RKS has four tanks as well: the fresh water tank, two gray water, and one black water tank.

The reason for this, as I understand it, is because this trailer has a rear kitchen and a central bath about 19'ish from one another. Instead of running the kitchen gray water into the same gray water tank as the bath, they simply separated the two tanks so that the bath gray water tank flushes the black water tank when emptied, and the kitchen gray water is dumped separately. It was something about piping the distance between the two drains. The tanks are also of a size that requires one dump of the black and gray water tanks for every two fills of the fresh water tank.