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Old 05-27-2023, 08:46 AM   #1
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Line Drain for tanks

Good morning! We are complete NEWBIES, in all sense of the word. The line drain pulls in outside control door, should they be pulled out or pushed in when we are parked? We are trying to rid the rv of drain smell and trying all possibilities.
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Old 05-27-2023, 09:11 AM   #2
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Your black valve should remain closed except when you dump. Grey lines can remain open. Some folks prefer to leave gray valves closed which is fine as long as you remember to dump. We keep our greys open until a day or two before we dump the black and then dump after dumping both of the black tanks.
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Old 05-27-2023, 10:21 AM   #3
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Not exactly on topic - but I make it a practice to drive with the gray and black tanks almost empty. That would be a lot of weight bouncing on the highway and they are not held up in the frame with sustantial support. Lots of folks here have added support for the tanks.
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Old 05-27-2023, 12:10 PM   #4
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The black tank drain should be pushed in (closed) when parked. You only want to open it when you dump. That way you achive a good hydraulic flow effect to get all the solids out. If you leave the valve open when parked, the liquids drain out but the solids don't. This results in the dreaded pyramid of poop and dried out mound that will block furture use.

The grey tanks (you do know there are two?) can be left open (particularly if you have a washer/dryer that drains to the shower tank) or closed (dump them before they get too full, ideally when you dump the black tank to help clean the drain line). If you leave them open (which we do), be sure to build a "trap" in the line to avoid a clear path for sewer gasses to return to the RV.

And one last point, If you weren't aware of the two grey tanks (shower and galley), then perhaps you don't know there are two separate pull handles. One in the convenience center which is easily found. The other is under the RV on the drivers side, somewhere near the wheels In front, between, or aft) depending on the model.
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Old 05-27-2023, 02:09 PM   #5
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Valves closed until ready to dump. As stated above, solids stay behind and liquids drain off ... EVEN in grey tanks. Soap skum, food particles, grease all remain behind causing smells.

I use an enzyme eater in my tanks after every dump. It takes only 1 ounce. It's designed for cleaning pipes in the house, but in addition to keeping pipes in the camper cleaned out, it also aids in breaking down any remaining solids that don't make it out of the tanks. The longer it sits in the tank, the better it does. This also helps keeps smells at bay.

Another trick you can try is to attach a Flush King valve on the end of your discharge outlet where the black and grey water come together. Attach the valve and dump the black tank. Now close the Flush King valve and open the grey water. This will "back flush" into the black tank. Let the 2 tanks equalize (about 10 seconds), close the grey tank now so no black water flows back into the grey tank, and open the Flush King and drain the black tank again. This back flushing will pull so much more "stuff" from the black tank, you'll be amazed.... especially when you see it through the clear section of pipe on the Flush King valve. Repeat this 2 more times with the grey water and your black tank will immediately be much cleaner. And this process takes no more time than normal dumping. I've been doing this on 4 different trailers for over 25 years now and never miss doing the back flush at least 1 time every time I dump the tanks.

Between the enzyme eaters and the back flushing, you'll get rid of the smells after a couple or 3 times of dumping.
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Old 05-27-2023, 05:57 PM   #6
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Look under your sink for a round black plastic "air admittance valve".
Sometimes they go bad and allow tank odors to come up.
To troubleshoot, put a baggie over it and tape/tie it closed tight. If the smell stops, that's it. You can take it to a hardware store to match it with a new one (keep the bag over the pipe to keep the smell out).
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Old 05-27-2023, 06:44 PM   #7
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Thank you all SO much!!! Have great weekend and stay safe!
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Old 05-31-2023, 02:19 PM   #8
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Drain Pulls

By the way, the drain pulls are probably not labelled--"IN" is closed, OUT is "Open". My very first trip I didn't know which was which, as my walk-through guy didn't point them out. Turns out they left all three full open, drain cap on. I hate to tell you what it was like when I removed the cap after three days to drain all tanks.... let's just say I should have had a snorkle and mask on!!
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Old 06-01-2023, 04:55 AM   #9
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Black tank should always be closed unless flushing the black water tank ..if you leave the black water tank open you will build a pyramid.. Grey water tanks should remain open
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Old 06-01-2023, 09:47 AM   #10
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We leave all tanks closed until ready to dump. We had a black tank smell our first couple trips out. Discovered that if I flush the black at least three times and then fill with three gallons of water and two pods there is no smell.
Tony & Donna
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