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Old 09-30-2013, 05:28 PM   #1
1 Rivet Member
1977 31' Sovereign
Huntsville , Texas
Join Date: Aug 2013
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Empty black water / greywater tanks dump valves

Bought a 77' Sovereign, first time owner, learning as I go. Its parked out in country now, no hookups. Previous owner said the GREY water dump valve needed replacing, so let's focus on the BLACK for now.

To dump the tanks, what are my options? How does the dump/drainage system basically work?

Do I need electricity? Running water? Can't I just spray a hose in the toilet to get things moving? If the "stuff" doesn't want to budge, can I use Lime or a chemical to break it up?

Or do I need a dump station get everything out?

Please help!

Much appreciated.

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Old 09-30-2013, 06:16 PM   #2
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1981 31' Excella II
New Market , Alabama
Join Date: Sep 2011
Posts: 5,284
Remove the cap on the outside and pull the little T-handles. One will be marked MAIN (Black Water) and One will be marked Axillary (Gray Water). Don't put your face where the end cap is and it might have smelly stuff behind it if the valves are bad. Don't ask Robin Williams to help you.

You want to flush the tanks with fresh water and then a bleach solution. Fill them all the way up mixed with 1/2 gallon of bleach and leave them that way for a couple of hours. Now flush again.


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Old 09-30-2013, 07:13 PM   #3
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2006 19' Safari SE
Tucson , Arizona
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You do not need electricity to dump the tanks... it's gravity-based.

Here's a step-by-step process for dumping the tanks...once you get the grey water tank useable...until then, skip the grey water part.

(1) Allow your black water holding tank to fill to about 3/4 full or better not fill so overflowing, obviously. If you need to add plain water to it get a good amount of liquid in the tank, that's OK. The more volume in the tank, the better the flush will be.

(2) Connect your drain hose (sometimes referred to here as a "slinky hose") to the large opening downstream from the grey and black valves ... and connect the other end to your sewer connection. Make sure all your connections are good and tight BEFORE you pull any valves.

(3) Pull the black water valve first. Let it drain and close it. If you'd like to do this process several times by filling the balk tank again with plain water to make sure everything is out ... or use Perry's suggestion for getting rid of anything left behind by the previous owner. If it had solids in it that were allowed to dry, you may have to work at loosening the stuff up. I would avoid really harsh solvents and chemicals for cleaning because you could damage seals.

(3) Generally, you want to wait to drain the grey water holding tank until you are finished with the black tank... In normal usage, this will clean out the slinky hose somewhat ... you can also rinse the slinky out with a hose. (Do not use your fresh water hose for this, though.) There is usually a rinsing hose available at dump stations. (If you are flushing the black tank until you get a clear out-flow ... then you don't need to "save" the grey tank for purposes of cleaning out the slinky.)

(4) When everything is drained to your satisfaction, close all valves and removed the slinky and replace the cover to the main drain. (This is when you can use the dump station hose to rinse out the slinky before disconnecting it from the sewer.)

(5) Stow your slinky, and away you go to your next destination.

If you want to use chemicals in your black water tank, that's fine. Lot's of folks do not. Because we live in a warm climate, I usually add a drop-in packet after dumping the black tanks and flush in a gallon or 2 of water to dissolve the chemicals. Chemicals will not kill odors completely but they help and they also help break down toilet paper and solids more quickly, which is a good thing.

I also add chemicals to the grey tank about every 3rd dump or so... via all the sinks and the freshens the traps and pipes and helps with oily build-up in the grey tank. Believe it or not, grey water can get pretty rank ... the longer it sits the more bacteria ...and odor ... develops. Keep your traps filled so grey water fumes don't come back into the rig.

Happy trails!
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Old 09-30-2013, 07:46 PM   #4
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2010 27' FB Classic
Austin , Texas
Join Date: Aug 2013
Posts: 111
If the trailer is movable, putting a partial tank of water in it and driving around awhile is a good way to break stuff up. If you really are out in the country, you can just dump that stuff out on the ground a little ways away from the house and it will absorb surprisingly quickly.
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