Why do we have separate grey and black tanks - why not one big tank?

[bucko]

Must be me. I get upset when folks walk their dogs and let them do their business on my yard. When I ask them to kindly pick it up, they tell me "its good for the grass". I then respond with "why don't you pick it up and toss it in your yard"?

Maybe I'll offer them my black tank drainage next time.

[videoarizona]

Not to polute the issue being debated here...but as a sailor who owns an RV...this discussion is really pointless. Reason? A huge ship can dump it's bilge and tanks in exchange for credits. We sailors can't dump our porta potties at all. Think about that. It's political.

As far as the original question, I go along with the separation of wastes answer as well as the structural answer. Add to that: It just makes more sense in many ways to have 2 separate tanks.

[Retired mountain folk]

Originally Posted by Ann-Marie

Why not one big sewerage tank?
It all goes to the same place when we dump it.
Our house just uses one system.
Wouldn't it be better to dilute the black tank with the nice soapy grey water?

Just a hint, drain your black water first then your grey water it will help to wash out your drain hose………..

[Vintner]

If you need to clean out your black tank try putting a bag of ice cubes down the toilet just before you leave. They scrape it out and then melt.

[berwin]

Dump the black tank and then use the gray tank to flush the hose.

[ccsest]

There is a large movement towards using household greywater for landscape watering Most things that go down our sinks, laundry drains and shower drains are beneficial to plant life. The same is true for RV greywater.

It is important that you know what is in the soaps and other products that go down your drain. avoid detergents and soaps that contain boron, synthetic fragrances, artificial dyes, bleach, and preservatives such as polyethylene glycol and phenoxyethanol. Sodium is also said to inhibit plant growth, and so, you should make sure that your greywater is free from it.There are, of course, conflicting opinions on if the greywater should be filtered.

I moochdocked in Georgetown, Texas last year for two months. According to the honey bucket truck I called to dump my black tank, greywater dumping is allowed there. The plants I was watering looked great when I left.

[Bayoutalker]

Let's put environmental issues aside. One reason for two separate tanks is if you are in a full hookup location. Putting all of your waste water in the same tank would fill it pretty quickly. If you have a sewer hookup you can leave the grey water valve open to allow it to drain until you are almost ready to dump the black water. Showers, washing dishes, etc use a lot of water. Toilets, not nearly as much so black water doesn't need to be dumped as often. We live in ours full time so that is our situation and we only need to dump once a week. If we only had one tank for both it would be a several time a week chore.

[jimmoore13]

Out west, where drought and wildfire are constant threats, using grey water to "water the trees" is infinitely more beneficial that any concerns about contamination in the grey water.

Don't pee in the shower...your black tank needs the liquid anyway...and the contents of the grey tank are: coffee grounds, small food particles, soap and water.

Soaps are surfactants and are frequently used as soil amendments. Dish soaps are used to clean contaminated wildlife.
These soaps are essentially harmless in the environment. Coffee grounds are innocent. In an RV, it makes sense to not just scrape dishes but to also use a used paper napkin/towel to wipe off as much food residue as possible before washing. So the concentration of food waste solids in grey water should be very small.

As others have said, out west you'll find that many NFS staff will encourage using grey water to water the trees. A camp hose at one location had an adapter on the grey dump with a garden hose connected that ran downhill about 25 or 30 feet from his rig. He had a hookup for blackwater, but he did not dump grey water into the septic on site (or it may have dumped into a vault toilet).

I usually use a 5 gallon bucket to haul grey water to dump sites around vegetation about 25 to 50 feet from our site...and I don't dump grey water directly on the site...no matter where I am. Each time I dump 3 to 4 gallons of grey water on nearby vegetation, it's as if there's been a major rain event for those particular plants.

I would no more "dump" grey water than light a match and throw it into dry grass.

In wet climates, however, conditions are VERY different. If the soils are saturated or nearly so, the grey water doesn't just soak into the soil and evaporate. It sits there. In those cirumstances, depending on camper population density nearby, I would NOT dump grey water onto the ground.

[craigav]

I highly recommend to use a fine mesh drain strainer for the kitchen sink, regardless of your grey water dumping plans. However, if you do plan to drain your grey water on the ground, having a strainer will help keep food particles out of the drain water. Some people also use a filter\strainer at the end of the hose as well, something as simple as old panty hose will catch most particles if the sink strainer didn't already do so. ~CA

[Johnynorthland]

I would think weight distribution might be a factor if you had one big tank.


I try and never travel with my gray tank full or with any water at all. Why carry extra weight!?


The black tank is a different story, I like to ensure it’s 2/3 full so there’s enough liquid for the 💩 to properly float out when I drain.


Just my two cents.

[LCBOYER]

You think??

[GABob]

Like a few folk mentioned above, using the gray water after the black helps to rinse the hose. What would you do to rinse with a uni tank solution?

[Dave A]

Originally Posted by Flashdman11

Everyone talking about "rules" and "laws" about dumping grey water but I would bet, if a man, they have went pee on a tree at some point.

I'm shocked! Outside? In the open? perish the thought

[garywilson]

Originally Posted by Flashdman11

Everyone talking about "rules" and "laws" about dumping grey water but I would bet, if a man, they have went pee on a tree at some point.

And, no tent camping allowed because when you wash dishes, empty your coffee pot, or bathe you get grey water on the grass...tsk tsk!

Cleaning fish? Oh my!

[8ballldl]

Without reading it all, this thread seems to have gone off down a tangential rabbit hole. To answer the question, it seems likely that it is because with the separate tanks you can first empty the blank tank and then the gray tank which rinses out the pipeline and hose with relatively clean and even soapy water.

[TaftCoach]

Originally Posted by bucko

Huh?

The gray water irrigates grass nicely. We use biodegradable cleaners, scrape our plates, avoiding all food bits and grease down the drains.

[TaftCoach]

Originally Posted by garywilson

And, no tent camping allowed because when you wash dishes, empty your coffee pot, or bathe you get grey water on the grass...tsk tsk!

Cleaning fish? Oh my!

It all went down hill when we moved out of caves. So much easier then.

[garywilson]

Originally Posted by Ann-Marie

Why not one big sewerage tank?
It all goes to the same place when we dump it.
Our house just uses one system.
Wouldn't it be better to dilute the black tank with the nice soapy grey water?

As you've probably noticed, 'why' gets all sorts of responses.

Everyone doesn't dump both tanks in the same place all of the time. Sometimes I wait until I get home to dump and rinse the black tank because I don't want to tie up a dump station while others are waiting.

If you want to combine both in your system, you can get the attached valve type that will fit your system and do so. Attach to your dump outlet, open both original valves, and it evens out.

https://www.amazon.com/Valterra-T58-...ve%2C82&sr=1-4

https://www.amazon.com/Camco-Holding...2&sr=1-25&th=1

https://www.amazon.com/Valterra-Degr...e%2C82&sr=1-29

[norty1]

My first trailer had only one tank for everything. The trailer sat high and the tank was not big to start with. First mod was to have another tank installed and piped all the sinks/ shower to it.
We could camp longer w/o dumping.
Now days there is not enough room under rigs for even one or two so the are shallow and take up lots is space.
We always let out a little grey back in the 60’s until people ruined it buy letting it all out anywhere. They now prohibit it to keep from stinking up the cg’s.

[bucko]

Originally Posted by norty1

They now prohibit it to keep from stinking up the cg’s.

This would be my main concern. That, and the "residue" that would sit on the surface of the ground.