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Old 04-26-2019, 04:37 AM   #1
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Your RV septic system learning to use it properly.

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There's nothing worse then stepping outside of your RV to the smell of someone else's rotting poop, all because of some bozo who doesn't know how to use an RV sewer system properly. Unfortunately I've had such an unpleasant experience on more than one occasion. Not used properly your septic system can get you kicked out of an RV park faster than any other feature on your RV because no one wants a stinky slinky hanging around including the RV park management. The popular nickname often used to describe the common RV sewer hose (stinky slinky). So I have published this article to help keep your stinky slinky from getting you in trouble and to keep your RV sewer system running right.

*Taking a close look at the RV septic system there are 2 tanks, black water for toilet and gray water for sinks, showers, etc.
*At the sewer hose connection the large knob is for your black water and the small knob is grey water. A common mistake people make is leaving their sewer valves open which is a defiant no no 😱. Always keep the sewer knobs closed except when dumping. This prevents the pyramid effect in your toilet which can eventually lead to serious plumbing problems. It also keeps your foul smell inside the holding talks where it belongs, not where your neighbors have to smell it. Leaving the sewer knobs open can quickly destroy your sewer hose and make it completely unusable.

*The only intended use of an RV sewer hose is to transport the sewerage from RV to the sewer connection in the ground and when dumping only.
*Only dump at a proper dumping station or through the sewer connection in your RV park when and only when your tanks reach 3/4 full. This gives any solid matter in your holding tanks time to break down and decompose. It also keeps your sensors working properly. A common problem with RV holding tank sensors. If toilet paper sticks on the sensor you might have to purchase a water wand and give your tanks a power wash at the sewer hose connection, or run your toilet for 1/2 hour with the black sewer knob open to give your black tank a complete cleansing flush.
*When dumping remember dump black water first and allow your tank to completely drain. Close the black water and then dump gray water to allow the soap suds from your leftover dish soap to clean the system. Once both knobs are closed use a toilet chemical like Camco TST orange treatment and put about a gallon of water in each tank. A couple of cap fulls of tst will work quite nicely after each dump. No more complaints about a poopy smell. If your a person with physical disabilities that has a hard time getting into such low spaces, consider having an RV professional install electronic dump valves on your system so you can operate your septic system from inside of your RV. Check your sewer hose at least twice a month for leaks. There made out of cheap plastic and are notorious for cracking and developing leaks that will have the whole RV park keeping your pungent order at the center of their attention. Keeping all the components of your septic system in good condition is key to enjoying trouble free convenience. So now that you know the proper industry standard etiquette for using your RVs septic system properly there is no excuse for your neighbors to ever smell your sewage again. Properly delivered from RV to the hole in the ground, that's how it will work when used properly. Hope this helps a lot of people learn the proper way of using the RV septic system.
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Old 04-26-2019, 05:01 AM   #2
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I suggest you Google “Septic System Definiftion”. RVs do not have a septic system. A septic system is a waste treatment system, RVs have waste holding tanks. There is a big difference between the two.
Marc and Jill, Wellington FL
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Old 04-26-2019, 05:35 AM   #3
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Nice write up for new owners and to remind those that have been around the block too many times. But there are couple of points for future reference. Nothing really wrong just something to consider.

1. "Leaving the sewer knobs open can quickly destroy your sewer hose and make it completely unusable." How would that happen?

2. "This gives any solid matter in your holding tanks time to break down and decompose." It takes days if not weeks along with the correct conditions of material, temperature, O2 / CO2 gas concentrations and a host of other factors before anything biological on a scale necessary to have any effect with regards to breaking down and decomposing to occur. Plus adding any chemicals for order control will further inhibit bio activity as an inadvertent side effect.

3. And as MRUSA14 stated leave the term "Spetic" off when describing the waste tanks. Holding and transfer, waste system and such are more accurate.
2006 Hurricane 31D built on a 2006 Ford F53
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Old 04-26-2019, 11:52 AM   #4
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It's not a septic system is it. Just a big bucket for storing poop until you can dump it, nothing is going to decompose or breakdown in there in the time it's stored.

Large knob / small knob, nope both the same size here.

I find most smell inside the motorhome is because the fan is on in the bathroom when flushing. Most smell outside is because there's no seal to the pipe coming from the ground. Buy a screw in connector or some plug that seals the pipe, or remove the hose and put the screw cap back on when not in use.

Other than that, good write-up
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Old 04-26-2019, 06:12 PM   #5
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I never drain my black tank unless it is completely full. More often than not I have to add water to fill the tank. The additional pressure created by a full tank will aid in forcing solids from the tank. I call it the "Whoosh" effect.
After draining the tank I refill it with clear water and dump it again. I will continue to do this until I see clear water passing through the clear plastic coupler I have hooked up to the tank discharge fitting. Once I'm satisfied the tank is clean I close the valve and add at least 4 gallons of water to the tank to keep the tank bottom wet.
You will never get a complete tank flush by leaving the black tank valve open and running water through the toilet into the tank. The water will just trickle down and run around any solids left in the tank. The sides of the tank will not get wet so any clogged sensors will not get cleaned off.
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Old 04-26-2019, 07:10 PM   #6
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We have been 6 months contionues use with both gray and black tank valves open.

Threaded connection to the CG fitting.

When do the bad things start happening ?

Wouldn't a partial full black tank smell thru the roof vent line ?
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Old 04-27-2019, 03:40 AM   #7
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i agree with what most have said, and i think the OP used the term "septic system" in a generic fashion...........that said, i believe waste storage/removal is one of the biggest "worries" a newbie will have, at least it was in my case..........what i learned is that it is "no big deal".............merely something that takes 5 to 10 minutes, maybe a couple of times a week............when we roll in to a campground, i wait until the black and gray tanks are nearing full, hook up the drain hose, pull black tank valve to drain, turn on rinse function for 5 minutes or so, close valve, pull gray tank valve, wait until it drains, close valve, close "water" door, and walk away.............if we are staying for a couple of weeks, i end up doing this a couple of times per week..............this isn't rocket science............when we are getting ready to pull out, if the tanks are more than half full, i will drain them...........if not, i will wait until we get to the next campground...............the biggest thing is "don't just hook up and leave tank drains open" long as we teach folks that, everyone is happy..................just my thoughts on a saturday morning................
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Old 04-27-2019, 09:14 AM   #8
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My DW & I found this guy's advise/knowledge pretty sound. We will be starting this system of "maintaining" our tanks on our next trip(s) out.
Pat, Becky & Katie (our Silky Terrier)
E. Wenatchee, WA
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Old 04-27-2019, 09:26 AM   #9
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I leave the gray open if staying more than a few days.

I also have a Flush King to flush both the gray and black.

Gray tank can get stinky if never flushed.
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Old 04-27-2019, 09:38 AM   #10
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I always open the gray tank dump valve first for a few seconds. I would much rather deal with a leak from the gray tank than the black tank.
Ernie and Shirley
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Old 04-27-2019, 09:40 AM   #11
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We have been leaving both of our tank valves open whenever sewer hookup is available. Just think of how many tank dumps I have not dealt with in 6+ years of full timing. Other methods do work with a little planning, like no paper flushed and 2 soap packets w/water on travel days to slosh around!
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Old 04-27-2019, 09:45 AM   #12
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Originally Posted by Ernie. View Post
I always open the gray tank dump valve first for a few seconds. I would much rather deal with a leak from the gray tank than the black tank.
that's pretty clever
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Old 04-27-2019, 01:07 PM   #13
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Anytime I see "always" and "only" used in an article about RV's I start to think about the number of different set ups that are used in the industry.

The Large knob / small knob for example. The factory put T handles on mine, both exactly the same size, one black and one grey.

The "flushing wand" works well, I suppose, for tanks where the toilet pipe drops straight down. However some setups have an elbow and piping that the wand doesn't fit in.

Only two tanks? How about the rigs that have three tanks? There may be only two TYPES of tanks, but many rigs have more than two tanks.

It's tough to make always and only statements that are true for all RV's.
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Old 04-28-2019, 01:10 PM   #14
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Threads like this just prove an old theory of mine.
"There is no such thing as an expert"
If you put two or more so called "experts" in one room they wouldn't agree on anything!
2002 Fleetwood Storm 30H on Workhorse P32 chassis 8.1 gas.
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