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Old 06-16-2015, 10:09 AM   #1
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Black and Gray water tank dumping

Just wanted to ask since i had a smell last week after dumping both tanks . Is there a proper procedure for dumping the tanks ? I have a switch for each one and a waste water flush switch .

Thanks Jerry

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Old 06-16-2015, 10:12 AM   #2
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I dump black then grey...make sure grey tank is pretty full so you have a good flush...then treat both tanks with one or two gal of water and chemicals..I use happy camper crystals and no problems with any smells

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Old 06-16-2015, 10:16 AM   #3
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bleach and fabric softener works for me....
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Old 06-16-2015, 10:24 AM   #4
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what does the waste water flush do ?
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Old 06-16-2015, 10:39 AM   #5
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Originally Posted by 1996VOGUE View Post
what does the waste water flush do ?
Run your waste water flush (usually has a separate hose hook-up) as you dump your black tank and when it is empty close your black valve and let tank fill at least 1/4 and open black valve again. I always get more brown stuff when I do that. (Clear plastic section in dump line allow me to see) Also run additional water through sink for gray tank and do the same. Black tank first, then grey. When you are satisfied, close valves, put treatment (Happy Camper works well for me) and add a couple gallons of water.
This works best when you have full hook-ups at site and not when you have others waiting behind you at dump station.
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Old 06-16-2015, 10:45 AM   #6
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Originally Posted by Late arrival View Post
I dump black then grey...make sure grey tank is pretty full so you have a good flush...then treat both tanks with one or two gal of water and chemicals..I use happy camper crystals and no problems with any smells
That about sums it up. Happy Campers does an excellent job and the cost is very reasonable compared to products on the market.

Most important, NEVER leave the Black Tank Valve open. This will result in solids buildup in the tank and you do not want that. Always try to have the Black Tank at least 1/2 full before you dump it. I always top it off with water from the tank rinse to at least 3/4 before I dump then run lots of water to give the tank a good flush.
Once you have dumped and flushed, run the flush for a bit with the valve closed to put 3-4 gallons of water in the tank, add your Happy Campers powder as directed, and off you go.
I use Happy Campers in the grey tank, through the sink drains, once or twice a year also. I do this with about a 1/4 tank of grey water just before heading out and let it slosh around while driving. When we arrive, I hook up and dump the Grey Tank right away.
If you don't have one yet, get yourself one of the clear plastic connectors that go between the dump valve connection and the slinky hose. This is a handy item so you can see what is coming off you tanks while dumping so you know you have them rinsed.

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Old 06-16-2015, 11:10 AM   #7
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Originally Posted by 1996VOGUE View Post
what does the waste water flush do ?
1996; there is a LOT written on the black and gray water flush, with some "how to" videos available too. And everyone has their own twist on the process, so read it all and think about what works for you. I'll share my procedure here, which has worked great for us for the past few years on two separate RV's, both of which we purchased new.

USING the toilets: We have found most of the drop-in types of additives work pretty much the same, and we do use them. Some of them say they are for "weekends" and others say they are good for "up to 7 days." I tend to plop one in every 3 days regardless. They are meant to provide a more pleasant odor, and they claim to help break down solids and tissue.

In addition to this, every so often I add about a cap full of liquid Calgon, plus a cap full of cheap liquid laundry detergent to a gallon or so of water. I pour this mixture down my toilet AFTER I have dumped the tanks thoroughly (see below), and I before I head home or to my next destination. This is loosly called the "geo method" (there are variants to this) but essentially this kind of cleans the side walls of the tanks, and it makes them more slippery so stuff doesn't tend to stick to the inside walls as much. I do this about every 3rd or 4th weekend of use--not every time. Some people ONLY use this and skip the chemicals.

In both of my RV's, if someone flushes the toilet while the bathroom fan is running, they regret it. The fan is strong enough to suck the air out of the black tank and fill the bathroom with terrible odors. So... fan off, then flush. No exceptions to that one for us!

Finally--flush with lots of water. We discovered that our toilet flush pedal has an "up" position too, that was not mentioned to us during our walk through. If you pull up on the handle, it fills the bowl with water but doesn't dump it. This is a nice way to pre-fill the bowl for the next person... and it helps assure that there is plenty of water to dilute urine and float the solids (see below).

This is the most common area where newbies make mistakes. When you set up camp, it is perfectly fine to hook up your sewer hose from your RV to the campground sewer, and if you want, you can open the GRAY valve so that shower water and kitchen sink water can go down the drain, into your gray tank, and straight into campground sewer.

Whatever you do... DO NOT open the black tank valve at this time! You want the solids from the toilet to be swimming in lots and lots of water in your black tank. Every flush provides water (hold down the flush handle longer than you think to add more water). But if you open the black tank while camping, the water will exit the black tank, but the solids usually will just sit there. Eventually, this builds up into what some call the dreaded pyramid of death! Use your imagination... not a pretty thing. If the solids sit in the tank for long, they become difficult to remove. So only open the black valve when you are flushing the black tank (see below).

My RV's have both had a garden hose connector for flushing the black tank. You can connect a garden hose to this and turn on the water supply. It sprays water into the black tank from a wand that spins around and around at the top of the black tank--kind of like the wand in the bottom of your dishwasher. Now... I turn on this hose EVERY time I dump my black tank. I usually dump my black tank when it's about 1/2 full (that's just how much we use it in a typical weekend), but I use this hose to fill up the black tank to about 3/4 or so. This involves turning on that water hose, then going inside my RV to frequently check the tank levels until I get to 3/4 full. Then I run out and pull the lever to dump the black tank.

I have a clear piece of sewer line connected between my RV and my sewer hose, so I can see what comes out. It's gross the first time you do it., to which I told myself to "Suck it up buttercup," cause that grossness is a good thing. It lets you know if you need to refill the black tank and dump it again. Typically the water clears up quite a bit after the initial surge, and sometimes by the end of the dump, the water is already clear. Sometimes I fill the black tank a second time--this time maybe only to 1/4 or 1/2 full, and that always returns clear-looking water.

NEXT... I close down the lever to my black tank and open up the lever that dumps my gray tank. This is just sink and shower water, but it can get smelly from grease or other food particles that you put down your kitchen sink. Usually it's just cloudy in color. There is no outside "fill" hose for this tank, and I never do anything other than to dump my gray tank. (I do pour some of the calgon/soap mixture into my kitchen sink when I do my black tank--which keeps the gray tank slippery and cleaner.)

These procedures have worked well for me. My tank meters are the original type that most RV builders uses, where you push the button and the sensors trigger red LED lights that indicate empty, 1/4, 1/2, 3/4, or full. These sensors on our first RV occasionally got dirty and would give a false read (tank wasn't 1/2 full, but it would read 1/2 full). That was when I read about the calgon treatment, and since starting that treatment, my LED's stopped the false alarm in the last RV, and have never triggered a false read in the new one.

Hope this helps. I know it's a little graphic, but hey, we're all adults here, and everyone poops!
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Old 06-19-2015, 02:09 PM   #8
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I'll add another variation. When I want to dump, I attach a third valve to the discharge, then a clear plastic section and finally the hose to the sewer. I hook up the hose to the black tank flush and turn the water on. Then, I open the third valve and the black tank valve. When the black tank is empty, I shut the third valve leaving the black valve open and open the grey valve. This allows grey water to run into the black tank. When both tanks are equal (I have a gauge for both in the wet bay), I shut the grey and open the third valve. This flushes the grey that had rushed into the black out the sewer hose. I repeat this process again using the grey water to clean the black tank. Finally, when both tanks are empty, I shut all valves, remove the third valve and cap the discharge. I then spray all fittings with Lysol, cap the discharge hose and store. The last thing I do is to shut off the black tank flush hose and store it. Inside the coach, I will add either Happy Camper or Pine oil to a full toilet and flush. This has kept the tanks well flushed and no odor inside. Next time I open the wet bay, it smells fresh and clean.
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Old 06-19-2015, 03:31 PM   #9
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i do the same thing, makes it super easy to drain the black tank.
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Old 06-19-2015, 06:58 PM   #10
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Originally Posted by Crasher View Post
.... I then spray all fittings with Lysol, cap the discharge hose and store....
Yes, the Lysol (or other spray disinfectant) is a good way to finish before capping and storing your hoses...
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Old 06-19-2015, 08:51 PM   #11
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If it was not already mentioned go to youtube and watch the video by the RV Geeks on flushing your tanks
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Old 06-20-2015, 08:27 AM   #12
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Originally Posted by noserider View Post
If it was not already mentioned go to youtube and watch the video by the RV Geeks on flushing your tanks
That's what I did before I bought my rv. I wanted to know as much as I could know before buying one. They have some great videos!
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Old 06-20-2015, 08:58 PM   #13
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I here so many folks that ad bleach to the black tank this is one of the worst things to put in the tank. Bleach is not a cleaner. It is a disinfecting agent. Why do you want to disinfect you black tank? The bacteria that will break down the waste is killed by bleach. A lot of the new tank treatment focus in adding bacteria. This will work if you don't dump often but I believe it's a good thing to have the bacteria in the tank as when you empty and rinse bacteria will remain in the tank and continue to break down the solids. The other negative to bleach is it degrades the integrity of the rubber seals. This will happen over time and will damage plastic components also. Bleach will make them brittle.
Keep the bleach for your fresh tank where you want to kill bacteria. Also don't over use bleach. Read the directions and use the proper amount.
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Old 06-21-2015, 07:40 AM   #14
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To answer 1996vogue,s original question, smell after dumping. We had that problem twice before we figured it out. After dumping full tanks a bad smell would waft out of the bathroom as we were driving. It turns out the water in the bathroom sink and shower trap was being sucked out allowing smell to come out. Could not find a vacuum breaker, now just pour water back into drains. Havent had that problem since. No mater how well you clean out tanks there will always be a residual smell.

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