Black and Grey Combined

[Fawudd]

I have had both black and grey tanks in TTs and now a Class B for years, and have never fully understood why there are 2 separate tanks these days. The fresh tank is always larger than the grey.....While boondocking recently, the grey filled up first and I had to dump, while the black was at 30% prompting the question once again. I know that some manufacturers combine them, but why doesn't everyone ?

[mkguitar]

the sizing works pretty good for us


I suppose it is so the grey washes the black from your hoses


Mike

[rogerstg]

There are scenarios where it's perfectly acceptable to let grey water run. Mainly on non public land. Sewer caps are available with a threaded hose end to facilitate this. It allows a length of hose to be used to direct the water away from the camper. That option is gone if you combine the tanks.

In the OP situation, one could have easily drained a bucket or two of grey water and dumped it in the toilet, thus delaying a trip to the dump station.

[avanti]

There are exactly ZERO good reasons for separate tanks to be routinely installed, I have owned both and would take a combined tank any day. This has been discussed at length previously on the list, so I won't repeat the arguments. The habit can be traced back to the days in which is was considered acceptable for a sink to dump out the bottom of ancient travel trailers. It is obvious that this is no longer appropriate--ever, and it is illegal in most places anyway. If one wants the ability to connect directly to a sanitary sewer so you can take continuous showers, this can easily be accommodated with appropriate plumbing. As far as I can tell, almost nobody does that with a B-van, though. DavyDD's current setup from ARV in which there are two tanks connected by a valve is a good compromise.

The real answer to your question is "Because that is how we have always done it."

[GeorgeRa]

Originally Posted by mkguitar

the sizing works pretty good for us
I suppose it is so the grey washes the black from your hoses
Mike

Originally Posted by avanti

There are exactly ZERO good reasons for separate tanks to be routinely installed, I have owned both and would take a combined tank any day. This has been discussed at length previously on the list, so I won't repeat the arguments. The habit can be traced back to the days in which is was considered acceptable for a sink to dump out the bottom of ancient travel trailers. It is obvious that this is no longer appropriate--ever, and it is illegal in most places anyway. If one wants the ability to connect directly to a sanitary sewer so you can take continuous showers, this can easily be accommodated with appropriate plumbing. As far as I can tell, almost nobody does that with a B-van, though. DavyDD's current setup from ARV in which there are two tanks connected by a valve is a good compromise.
The real answer to your question is "Because that is how we have always done it."

For 35 years we had separate black and grey tanks and found that drain hose flushing with grey water to be good sanitary process so for that reason we would still prefer separate tanks.

With sealed hose macerator pump discharge separate tanks could reduce the need for flushing, but I still doubt how good the hose sealing process really is, right after the hose is removed from the drain hole it is not sealed.

This unsanitary hose handling issue could be eliminated with fresh water hose rinse system built into an RV’s drain plumbing, but fresh water contamination could be an issue.

[avanti]

Originally Posted by GeorgeRa

With sealed hose macerator pump discharge separate tanks could reduce the need for flushing, but I still doubt how good the hose sealing process really is, right after the hose is removed from the drain hole it is not sealed.

I agree that flushing is important with a gravity dump system. I have a tendency to (wrongly) assume that everybody has a macerator these days, since that is all I have every had. However, there is really no issue of building a system that really is fully sealed, and I find putting on the tiny cap at the end of the dump hose to be a non-issue.

[booster]

Originally Posted by avanti

I agree that flushing is important with a gravity dump system. I have a tendency to (wrongly) assume that everybody has a macerator these days, since that is all I have every had. However, there is really no issue of building a system that really is fully sealed, and I find putting on the tiny cap at the end of the dump hose to be a non-issue.

Our macerator has a clunky PVC ball valve on the end of it which is pretty convenient as you don't handle a dirty cap, but it also leaves the short distance from the valve ball to the open air not sealed. We normally haven't been rinsing that short end, but probably should start doing that. It rides in it's own little compartment so can't contaminate anything else, but still could probably use a rinse. We hand hold it above the dump drain so no contact there which probably helps us, but takes two people most places.

[avanti]

This is the style that we have always used:



The system is sealed with hose-clamps or threaded fittings end-to-end.

[Davydd]

We have a macerator with a dumping hose attached at the van end and a quarter turn valve to open or close at the dumping end with a 3”, 4” and cone assortment of attachments to close the system if required.

We do have separate grey and black tanks. One advantage of that is to clean out hoses, especially 3” slinkies that detach by dumping black followed up with realities clean soap laden grey. Maybe that isn’t as important with a closed macerator system. We do have the ability to open a valve and distribute waste water evenly over a combined black and grey but so far haven’t any desire to do so since we have a total of 51 gallon capacity of Grey 26, black 25.

There is a critical need for two tanks with gravity dump toilets that need to be directly over the black tank. Placement of tanks are limited in Class Bs. I can tell you that you can get greater capacity by separating the tanks for optimum placement in the available space under a van. Grey tanks can be more independently located. I kind of eliminated that need with a macerating marine toilet with a remote black tank not dependent on location under the toilet.

With a macerator I am apt to dump more frequently or when convenient because of the clean closed system than with an old 3” detachable slinky hose that sometimes has to be rinsed despite the separate grey water follow-up.

[RossWilliams]

I think you answered your own question. I think most people run out of grey water space first. But doing without the toilet is a lot less convenient than not being able to take a shower. So two tanks allow you to continue to use the toilet until you have a chance to dump the tanks.

And given the accuracy of tank gauges it's not all that easy to always have to monitor the tank level and dump before you run out of space.

[avanti]

Originally Posted by RossWilliams

So two tanks allow you to continue to use the toilet until you have a chance to dump the tanks.

...and a single tank allows you to continue to use whatever capacity remains, without having to make assumptions about which tank "most people" run out of first. This is the best single argument for a single tank (or two interconnected tanks such as DavyDD's, which is much the same thing).

[Modersical]

We should have separate grey & black tanks.

As you mentioned, the grey tank fills first; since many parks have no sewer hookup, most allow grey water to be released to the ground, usually through a garden hose, attached to the gray tank discharge.

This allows you to go much longer before needing to go to a dump station, since the black tank fills much more slowly.

Some misconceptions cause some parks to not allow this; but it is allowed at many parks with no untoward results/problems! It is acceptable at some city parks, some county parks, & some federal parks, including COE Parks on a River, in a suburban area.

[booster]

Originally Posted by Modersical

We should have separate grey & black tanks.

As you mentioned, the grey tank fills first; since many parks have no sewer hookup, most allow grey water to be released to the ground, usually through a garden hose, attached to the gray tank discharge.

This allows you to go much longer before needing to go to a dump station, since the black tank fills much more slowly.

Some misconceptions cause some parks to not allow this; but it is allowed at many parks with no untoward results/problems! It is acceptable at some city parks, some county parks, & some federal parks, including COE Parks on a River, in a suburban area.

Maybe 20 years ago, but at least in the places that we go I don't think we have run into any that allowed grey water to be dumped on the ground, in at least 5 years.


We must use water differently, as our 10 gallon black tank always fills at least twice as fast as the the grey tank.

[avanti]

Originally Posted by Modersical

We should have separate grey & black tanks.

As you mentioned, the grey tank fills first; since many parks have no sewer hookup, most allow grey water to be released to the ground, usually through a garden hose, attached to the gray tank discharge.

This allows you to go much longer before needing to go to a dump station, since the black tank fills much more slowly.

Some misconceptions cause some parks to not allow this; but it is allowed at many parks with no untoward results/problems! It is acceptable at some city parks, some county parks, & some federal parks, including COE Parks on a River, in a suburban area.

Respectfully, almost everything stated above is incorrect. Although there are exceptions, gray water dumping is prohibited almost everywhere, most especially in defined campgrounds.

Picking the COE as a typical example:

327.9 Sanitation.
(a) Garbage, trash, rubbish, litter, gray water, or any other waste material or waste liquid generated on the project and incidental to authorized recreational activities shall be either removed from the project or deposited in receptacles provided for that purpose. The improper disposal of such wastes, human and animal waste included, on the project is prohibited.

https://www.usace.army.mil/Portals/2...1165-2-316.pdf

You will find similar regulations defined for almost all government agencies. There is no misconception.

Even in the few places where it is technically legal, almost nobody these days considers it to be responsible, due to its effects on the local ecosystems. Even backpackers filter their wastewater and carefully disperse it in small quantities at any given location. The filtered material is carried out.

Please don't dump gray water.

[Modersical]

Originally Posted by booster

Maybe 20 years ago, but at least in the places that we go I don't think we have run into any that allowed grey water to be dumped on the ground, in at least 5 years.


We must use water differently, as our 10 gallon black tank always fills at least twice as fast as the the grey tank.

Perhaps you potty more than you shower!?!

Actually, at the COE park last month, near Little Rock, AR, it is common practice to drain water under the mature trees of the park . . . A beautiful, well cared for park. Last year at a county or city park in Lafayette, LA the same; and in Jonesboro, AR’s beautiful city park in AR, it is allowed with no problems!

Now, as to how rapidly the black tank fills compared to the grey tank, our class A Winnebago, that we currently have, has an electric toilet in the back bathroom; and it does use much more water; but our grey tank still does not fill near as fast as the black tank.

[avanti]

Moderator's note:
Advocating illegal activity violates the list's terms of conduct. I will let the above messages stand, since they are rather mild, but any further messages along these lines will be deleted.
--Your site team

[Davydd]

There is a misconception about what grey water is. It is not just water and biodegradable soap. It can be food waste, grease, and just about any liquid that can be poured down a sink. In other words, liquid garbage. Campgrounds are concentrated areas and anyone disposing grey water on the ground is essentially creating an environmental cess pool. Grey water belongs in a sanitary sewer.

[avanti]

This thread is closed.