Why do RVs need separate grey and black water tanks ? Does your coach ?

[someguy]

Why do RVs need separate grey and black water tanks ?  Does your coach have separate tanks ?

[Knuckles]

I know new airstreams the most expensive ones have one tank because they have macerater toilets and seeing everything is liquid only have one big tank and one freshwater tank. Not sure whether new rvs have followed their example yet

[richard5933]

Combined tanks were quite common at one point early in the RV industry. Then everything had split systems. Now I'm seeing combined tanks again.

Both our first bus and our current one had combined gray/black tanks. Never had an issue with the setup. Our current setup is side-by-side fresh and waste tanks, each 90 gallons in size. We operate off the fresh tank with our onboard pump, even when in a campground. Makes it easy to ensure that we never overflow our waste tank.

Having a combined waste tank makes dumping quick and easy, even through the 2" discharge port on our tank. The contents are always well liquefied and we've yet to have a clog. No macerating toilet on ours, but the end result is about the same especially after driving a few miles with the tank partially full.

In my estimation, the only time separate tanks would be helpful is if you plan to dry camp frequently in areas where it's possible/legal to dump the gray water to the ground in some fashion. That seems more common in the West and Southwest, much less so east of the Mississippi.

I've yet to see places where one must dump gray & black separately, but I have heard of some that will covertly dump their gray water into sewer drains or while driving. Not recommended in my opinion.

For some, installing separate gray/black might make it easier to maximize available space, but from what I've seen it's usually possible to do this with a combined tank as well. There is also far less plumbing with a combined tank.

If you are planning to camp in an area where dumping to the ground is possible, I would suggest simply plumbing the shower & sink through a diverter on the way to the waste tank. When you want to dump to the ground, switch the diverter valve and have the gray waste go through the plumbing directly out.

[Utahclaimjumper]

A common practice with twin tanks is to use the gray to rinse out the black piping after dumping..  I have had both and like the twin setup..>>>Dan

[luvrbus]

They both have advantages and disadvantages separate tanks work better for camping since gray water tanks use more water and fill faster and most places in the desert let you dump the gray water,Fresh water is what you worry about boondocking I have seen people in Quartzsite camp for months but they were always carrying water in jugs ,I have had both and prefer the 2 tanks system macerator equipped toilets are a real pain to maintain and parts are exspensive for one   

[someguy]

Thanks for the replies.

I've never heard of campsites that would allow one to dump grey water (on the ground ?) but not black water.

It certainly would eliminate a lot of plumbing to have one tank for everything.

[usbusin]

I've never heard of campsites that would allow one to dump grey water (on the ground ?)

I.

Have you ever been to the desert?

[someguy]

Have you ever been to the desert?

Never camped there, no.  I'm glad I asked about this.

[Utahclaimjumper]

Many high mountain areas also allow it in remote unimproved spots..>>>Dan

[neoneddy]

Ours is black and fresh only, works fine, keeps us out of trouble  with overflowing anything.

I have considered having a diverter valve for the sinks / shower to rain directly to the ground in remote boondocking situations .

Here is my take on grey water.   Is it bad to wash your hands or dishes outside on a table and dump the water to ground?  I see no problem.  Now what if you use a bigger bucket and collect the water and dump every few days.  Now what if that bucket was a tank .... you see where this is going.  Just my $.02  Scale shouldn't change it, at least the scale we do it. 

[lvmci]

I have had both grey/black and separate  grey and black. The combination G/B built up more volume and emptied quicker, but when it overflowed into the shower it was quite unpleasant.
The seperate tanks take longer to empty, but if you empty them in the right order, you can back wash the black tank with grey water, eliminating dry caking buildup and put some water back into the black tank with you deodorizer/anti caking chemicals to swish around and cleanout the black tank on the way back home, without using clear water...vertical shaped tanks are always more efficient at getting very ounce out, lvmci...

[richard5933]

...Here is my take on grey water.   Is it bad to wash your hands or dishes outside on a table and dump the water to ground?  I see no problem.  Now what if you use a bigger bucket and collect the water and dump every few days.  Now what if that bucket was a tank .... you see where this is going.  Just my $.02  Scale shouldn't change it, at least the scale we do it.

There can be lots of nasties in gray water, especially coming from the shower/bath. Fecal matter, body fluids, etc. can make for some really powerful stuff if left to ferment in the heat in a tank for a while. My reading shows that besides fecal matter, there can be bacteria, viruses, and other pathogens in the gray water.  I'm no biologist so I can't make a statement regarding the safety of dumping gray water to the ground, but I'm sure that a case could be made either way.

[neoneddy]

There can be lots of nasties in gray water, especially coming from the shower/bath. Fecal matter, body fluids, etc. can make for some really powerful stuff if left to ferment in the heat in a tank for a while.

is there anything wrong with using a tent outdoor shower?  Same thing.   Sure it doesn't sit in a tank, but if you dump directly to the ground with a diverter valve I see no difference.

My reading shows that besides fecal matter, there can be bacteria, viruses, and other pathogens in the gray water.

I've heard the same about lakes in general.  Be careful going down tubing / floating rivers on the weekends :-)

[buswarrior]

The discussion needs to be whether the local authorities will allow gray water to be dumped to the ground...

All the justification and explanation, right or wrong matters not if the ticket book comes out.

Happy coaching!
Buswarrior

[Fred Mc]

My first camper had a macerator toilet. Worked fine until it
Didnt and i had to fix it. That was45 years ago and at that time I promised myself i would NEVER have another-a promise im proud to say ive kept. Im sure that macerator toilets have
Improved over the years but the contents are still the same.
Thanks but no thanks.