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Author Topic: Emptying the Holding Tanks  (Read 535 times)

Albert64

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Emptying the Holding Tanks
« on: August 29, 2017, 10:24:53 AM »
My wife and I just purchased our first RV. It's a 2005 Dutchmen Class C and we are preparing to head out on a short trip, not too far from home, just so we can start learning how to use all the systems on this rig. The folks we bought the rig from were very kind and helpful and spent several hours going over all aspects of the RV, but after awhile you reach a point where it all seems to become overwhelming (I felt like my head was ready to explode!). I've been going through the owners manual and I'm finding that the more I read, the more questions I have. My first question has to do with emptying the holding tanks. I read Gary Brinick's (sp?) terrific article laying out how to dump the waste tanks. In it, Gary recommends not emptying the black water tank until it is at least half full, and my owner's manual suggests it be 3/4 full. My owners manual recommends putting enough water back into the black water tank to cover the bottom to prevent hardening of any residue that may remain in the tank. My question is, if my black water tank holds 37 gallons, how much water should I add back to the tank to cover the bottom? One Gallon? Two Gallons? Five Gallons? Thanks for the help, we definitely appreciate it!

Rene T

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Re: Emptying the Holding Tanks
« Reply #1 on: August 29, 2017, 10:30:40 AM »
I usually wait till the tank is at least 2/3 full but that's not much different than 1/2 or 3/4.  Once you're done dumping, add around 5 gallons of water. That's not real critical either. 4 gallons will work and 6 gallons will work. The thing is to have enough water in there to start the breaking down action once you start using it and it also helps break up anything that may have not been flushed out when you dumped.
Rene & Lucille & co-pilot Buddy
AKA  Pep N Mem
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& Florida Snowbird in Lakeland FL

Albert64

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Re: Emptying the Holding Tanks
« Reply #2 on: August 29, 2017, 10:42:20 AM »
Thank you so much Rene! We appreciate it!

SeilerBird

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Re: Emptying the Holding Tanks
« Reply #3 on: August 29, 2017, 12:24:57 PM »
I usually count to one hundred when the tank is empty. Then count to five as I hold the flusher.
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ArdraF

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Re: Emptying the Holding Tanks
« Reply #4 on: August 29, 2017, 05:46:47 PM »
The main thing is to be sure there's some water in the bottom of the tank once it's empty, otherwise anything left in it after dumping can harden which you don't want.  You also don't need a lot of chemicals.

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Joezeppy

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Re: Emptying the Holding Tanks
« Reply #5 on: August 29, 2017, 07:56:33 PM »
If we are staying somewhere for a week (or more) and I am emptying the tank mid-week, I don't necessarily add any water. I figure we'll flush soon enough to keep things moist. At the end of a trip, I'll add about 5 gallons. It's not a scientific number - I just figure it's enough to slosh around on the ride home and clean off the bottom of the tank.
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chindog

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Re: Emptying the Holding Tanks
« Reply #6 on: August 29, 2017, 08:55:11 PM »
The reason for having 1/2 - 3/4 tank full before flushing is to get that gravity fed "whoosh" that sucks all the solids down the tube to the dump station orifice.  When I first heard of this, it reminded me of Ross Perot talking about "that giant sucking sound".  But, your gray tank will also have some solids that accumulate.  When you wash your dishes, there are small food particles that go down that drain.  If you leave your gray tank open, those particles can accumulate and clog up your gray discharge line.  I know from experience.  So, now I usually leave my gray tank valve shut until I build up at least half a tank.  Exceptions are when my wife is using the washer (valve is alway open to prevent accidental overflows), and dumping before hitting the road no matter what the level is.
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Rene T

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Re: Emptying the Holding Tanks
« Reply #7 on: August 29, 2017, 09:56:01 PM »
But, your gray tank will also have some solids that accumulate.  When you wash your dishes, there are small food particles that go down that drain.  If you leave your gray tank open, those particles can accumulate and clog up your gray discharge line.  I know from experience. 

I've been RV'ing for 35 years and have always left my gray water tank valves open and (knock on wood) never had any issues with clogging up. Maybe I'm just lucky or you were unlucky that one time.
Rene & Lucille & co-pilot Buddy
AKA  Pep N Mem
2011 Chevy Duramax 2500 HD 4X4
2011 Montana High Country 343RL
From the Granite State of NH
& Florida Snowbird in Lakeland FL

ArdraF

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Re: Emptying the Holding Tanks
« Reply #8 on: August 30, 2017, 04:34:02 PM »
We tend to leave our gray tank valve open until we're getting ready to dump the black.  Then we close it and let the gray water accumulate for a day or two.  We just did an experiment on our last trip.  We emptied the tanks and closed the gray after dumping.  I did one load of wash in the Splendide and it filled about a third of our gray tank.  We've started the experiment before but never remembered to check the gauge at the end of the washing/drying cycle.  ::)

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Albert64

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Re: Emptying the Holding Tanks
« Reply #9 on: August 30, 2017, 04:37:16 PM »
Thanks for all the terrific recommendations! I find it all very helpful. We are venturing out on a short trip on Friday and I'm sure it will be a terrific learning experience!

dmiller226

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Re: Emptying the Holding Tanks
« Reply #10 on: September 01, 2017, 04:26:11 AM »
I read here and on a couple of other places on the forum about putting some water back in the black water tank after dumping. If I dump prior to leaving our site for home and won't be bringing the camper back out for a few weeks, should I still be putting water back in the tank? Always keep a small amount of water in it?
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Gary RV_Wizard

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Re: Emptying the Holding Tanks
« Reply #11 on: September 01, 2017, 05:03:23 AM »
Generally a good idea to keep a few gallons of water in it. That assures that any solids & paper will dissolve and stay dissolved. Not real important if you know the tank is empty of such things, but one never knows when the need to use the commode might arise.
Gary
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HappyWanderer

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Re: Emptying the Holding Tanks
« Reply #12 on: September 01, 2017, 11:56:39 AM »
I don't think that solids left behind in the gray tank present a danger of clogging the drains as much as the potential for odors. That's the main reason I leave ours closed except to dump, to make sure everything is flushed away.
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