Black Tank or Grey Tank, Which Do You Drain First

[Sundancer330]

You may be surprised at this answer, the following is a blog from Makarios RV.

Some may agree and I am sure many won't but it was an interesting read.

Camping RV Blog
Posted by Claudia Haddix on 30th Jan 2018


Recently I was attending a seminar and an interesting question was posed, one that I thought I surely knew the answer to. "When dumping do you empty your black tank or your gray tank first?" Gut reaction and what I had preached for years, (Yes I have dumped both tanks before!), BLACK! When I explain the reasoning that this is false you will be understand.



The speaker went on to correct everyone that shouted a resounding Black that you should actually dump the gray tank through for an allotted time to get the black plastic pipe good and we,t like a slip and slide so that any "gunk" coming out of your black tank slides right on through the pipe and into the dump station. It makes perfect sense when you think of it. Moving anything with any substance through a dry plastic pipe is going to rely on the pressure of your water moving it through. When anything with substance moves through a wet and soapy lubricated pipe it is going to be less likely to stick around and make your pipe stinky.

Brilliant! So my new routine is to dump my gray tank first and let it run through the pipe for a few minutes then empty out the black tank and then back to the gray to flush whatever is left all the way out.

[33 RLDS]

Nah, I will stick with black first when I'm not using my macerator. Black is 95 % liquid anyway.

[RedHorse1]

I can see his point but like 33 points out, Black stream is mostly liquid. Black first.

[Force]

Even if I did agree with that, running your gray for all of 10 seconds would accomplish getting the hose wet.

So would spraying it with a hose before you hook it up for that matter

[wags999]

That explanation sounds like one an academic would give, all theory but no practical experience. I agree with the second opinion, a black tank is almost all liquid very little actual solids, especially if treated and given a few days. And any small amount of solid stuck in a hose, would quickly be carried away with the gray tank is fully open and dumped.

In theory many things seem logical, but, in practice many times those theory's are easily proven wrong.

[Rice1951]

Next thing you know is they’ll want us to change our diet so it will make up the right composition of material matter that ends up in the black tank.
Thanks but no thanks. I’ll just keep doing it the way I’ve been doing it for the past 30+ years just because...........well just because it works.

[WinnieView]

Hmm...It's called a stink pipe for a reason.

Sometimes it's more convenient to dump the grey tank before leaving a camping location and then dump the black later.

Use the black tank rinse and away go troubles down the drain.

[Force]

Sundancer...all our responses aside, thanks for sharing, always interesting to read new ideas and/or challenges to conventional wisdom

[wabirch]

I'm putting away a sewer hose that is better rinsed off afterwards by a garden hose than what a grey water tank will provide, nope.

[North of 49°]

We always have a much larger volume of grey water than black water, so if there's anything stuck in the hose after dumping the black, the large amount of grey that is soon to follow will flush it out. Plus, I always rinse the hose out when I'm done. Always start with the dirtiest water and rinse with progressively clean water. I understand what the speaker was getting at, but I think it was a solution in search of a problem.

[WeRJuliian]

Am I the only one who opens both dump valves at the same time?
(And then run the flush, and hose out the dump pipe after I unhook it)

[wags999]

Originally Posted by WeRJuliian

Am I the only one who opens both dump valves at the same time?
(And then run the flush, and hose out the dump pipe after I unhook it)

That's a good way to get black gunk in your grey tank.

Not something I would want to happen, even being remote.

[Flyrotor]

Hmmmm, No, I’ll stick to my regularly scheduled program

[LesBevil]

When we first purchased our TT, the salesman told us to always add a couple of ounces of dish detergent and 2-3 gallons of water to the black tank before heading out. To me that makes the black tank "slick" so the solids shouldn't stick in the hose. Then dump grey which is mostly soapy water and finally flush the hose. If I'm concerned about the dump connection (I've been at a couple of campgrounds where the connection is iffy to say the least) I'll open the grey (for a second or three) to make sure the hose will stay connected before I open the black. Better to have soapy water that poopy water on the ground!

[Swardy]

I get the logic behind this and would give it a try IF I had a problem to solve. Seeing as I have never had a problem with Black > Grey > Hose rinse, I'll probably stick with it.

Sometimes solutions are found to problems that don't really exist.

[Scott91370]

My grey tank merges with the black tank about 6" from the discharge opening so I don't think it would make much difference.

[Mustang65]

Sounds like a possible "POLL" to be started after reading this.

Black tank first, Gray tank 2nd. My reason is that it flushes out any debris from the black tank in the hose. I also rinse the hose out. Now that we are switching over to seasonal, I still use the black/gray tanks and run the tank sprayer every Thursday at 10AM while doing the weekly dump. No problems with poop mountain this way, as some of my seasonal neighbors have.

Don
My Registry

RVing with SOLAR

[richie t]

I add some fabric softener and some water into the black tank before heading out. All that sloshing around keeps everything moving smoothly.

Sent from my 9020A using Tapatalk