Gray Water Discharge? 2016 Via 25T

[JTR]

I have just recently rejoined the RVing community with the purchase of a 2016 via 25-T after a long sabbatical. I was very curious to learn that it uses a macerator pump to discharge the gray water. After thinking about it I thought it was a stroke of genius as they were using the gray water to flush the blackwater tank, as they both use the same discharge connection to the sewer. But after further investigation I've learned that that's not the case at all; they are simply pumping the gray water and merging it to the blackwater tank connection.

I have two questions that I hope someone can shed some light on:
#1- Why is a macerator pump required to discharge the gray water? Gravity seems to work very well and there is actually a plug that can be replaced with a garden hose connection to eliminate the pumping process; which I plan to do.
#2 - if the gray water is going to be pumped and both the gray water and black water tanks are going to utilize the same connection, why isn't the gray water discharged into the top of the blackwater tank to help flush the black water tank during the dumping process?

Seems to me they missed a great opportunity to facilitate the dumping process.

Here again I'm new to this community and any insight and this wouldn't be most appreciated.

[creativepart]

The simple answer is you don’t want to accidentally overflow the black tank by dumping your gray water into the black tank. What you suggest would only be feasible if there was some mechanism to prevent a user from dumping a full gray tank’s contents into a too full black tank causing it to overflow. And, of course there is no such mechanism to prevent that from happening.

The tanks are not always at optimal downward slope for gravity dumping so the macerator includes a pump to better empty the tanks.

If you dump the black tank first and dump the gray tank last you help clean out the dump hose with the gray water. But you always keep the respective tanks separate.

There are some people with some RVs that like to merge the contents of both tanks to have more gray tank capacity for Boondocking. But I don’t believe that is a very widely accepted practice.

[Eagle5]

Hi JTR,
After reviewing your Owner's Manual (starting on Page 7-10), it would appear that:

1. There probably is insufficient room for a standard-diameter Gray Tank drain-line, so a smaller-diameter macerator pump drain-line is used for the confined space.
2. The Gray Tank is kept isolated from the Black Tank as is traditional in most motorhome septic designs. Also, access to the top of the Black Tank is probably not possible, with the exception of the toilet itself. Since you would need to plumb-into the side of the Black Tank somewhere, it could back-feed into the Gray Tank when the Black Tank becomes full.

Eagle5

[Seymour2Lane]

Greetings,
On our Sprinter based 2016 View, our gray tank is located behind the rear axle, necessitating a macerator pump to send the gray water forward over the axle to the dump valve.
Also, as others have done, I replaced the gray tank low point plug with a hose valve as a back up to a pump failure.
Welcome back to the forum, Mike

[JTR]

Thanks Guys...
I think each of you have made reasonable explanations. I guess it is a routing/piping issue but I do believe there could have been a better solution. Even swapping the black and gray tanks if a macerator pump is required. From my experience the black water tank could be half the size that it is since far more volumes of gray water is used in camping than black water. Swapping the tanks and reducing the size of the black tank would also lighten the load behind that rear axle.... makes a lot of sense to me.

That would require the toilet to be located further back... Perhaps other floorplans with the toilet further back could demonstrate that arrangement.

[Morich]

The problem with trying to make changes in the smaller RV is that the spaces have to conform to other things which are even more vital to get right.
When we look at where they put the tanks and ask why, it becomes a question of how to get around things like the axles, springs and driveshaft that are really even more important than the tanks!
Then when we look at what it does if we move one item, it becomes a cascade of small changes that can wind up with big issues.
Swap the black and grey tank locations sounds simple but then we have to look at the cascade it starts!
We keep the stool over the black to avoid clogs? But if we move the black tank to under the bed, where the grey fits, how do we avoid a stool in the bedroom? The bed is a biggie that takes a lot of room, so very hard to change it!
IF we could change the black location, then it cascades into moving, turning the shower and vanity sink! We want to keep them in the same room for many people, so that gets really tricky if we move the whole bath to the back as we have to move the whole bedroom forward and that extends the total width of the RV, left/right!
That makes us have to move the stove, frig and wardrobe! But if we move them, we still want the sink next to it in the kitchen that we just moved to the back? Do we want the bedroom between the dinette and kitchen? Crawl across the bed with the morning coffee??

It gets past talk and big ideas and involves who can actually DO something!

So it gets tricky and we need to actually build a model mockup and see if it all fits!
I'm guessing they did a lot more thought about those than we will ever know!
It gets lots harder to actually do things.
If it's easy, somebody else is doing it already!

[JTR]

Yeah....I got all that but reducing the black tank by 50%, which is more than enough, sure would be a good place to start start. I've owned five campers and I've said that about every one of them I've ever owned; the black tank is entirely too large the gray tank is entirely too small. For several years I took my family to Oshkosh where there was nothing but dry camping available. I had friends rope off a spot adjacent to one of the few little patches of woods around so I could snake a garden hose into the woods from my gray tank. My black tank would never fill up.

[reckless37]

Hi-

I have a 2011 Via 25Q and after purchasing it last year. Soon after I had difficulties getting the grey water to empty. I found a post where someone added a valve to dump it from the rear. I did add a post about my experience. It has the disadvantage of having to move the dumping hose between dumping the black and grey, and the advantage of dumping much faster (since you are dumping out of a full-size valve, and not having to pump it via a small hose to the front).

BIGB came up with the idea of possibly modifying the old pumping line to transfer grey water to the black water tank - to solve the problem of the grey tank being too small and the black being too big. This would involve moving the hose and plugging the current spot. I don't if anyone has implemented this idea, but it would be nice.

[bigb]

I never added a way to pump from gray to black because I never needed it but I did add a 3" drain to my gray tank with a garden hose nipple on the cap which makes it extremely easy to keep the gray water tank empty without fussing with the slinky. I made a sewer cap with a GHT fitting and I carry an orange garden hose for gray water and black tank rinsing only.
I never even use the pump anymore except once in awhile to keep it from seizing.

[bigb]

PS if you wanted to transfer some gray to black all you need to do is add a wye in the white pump line where it passes by the black tank on the frame rail and two valves or a wye diverter valve then punch a hole in the top of the black tank. But as I stated above I didn't find it necessary plus it could potentially cause problems such as leaks, over-filling/over-flowing or backflow, and the valve(s) might be difficult to access without laying on your back, not to mention it doesn't look easy to get to the top of the black tank, the entire 1/4 of the top of the tank is surrounded by structural steel. (I wish Winnebago would have plumbed the bath sink to the black tank) The garden hose mod is wonderful and makes life easy for us.

You could also reduce your macerator pump winter drain down to GHT and put a cap on it, then attach your hose there and pull the 2" blade valve but leave the pump off. I did this as well (see my pic above) but I don't use it as the hose fitting on the cap is much easier.

[4x4van]

Originally Posted by JTR

Yeah....I got all that but reducing the black tank by 50%, which is more than enough, sure would be a good place to start start. I've owned five campers and I've said that about every one of them I've ever owned; the black tank is entirely too large the gray tank is entirely too small. For several years I took my family to Oshkosh where there was nothing but dry camping available. I had friends rope off a spot adjacent to one of the few little patches of woods around so I could snake a garden hose into the woods from my gray tank. My black tank would never fill up.

And I have had the opposite problem. With a family of 5, in all 3 of my RVs, my black tank would fill first. Since we would seldom shower inside while boondocking (used an outside hanging solar shower bag instead) grey wasn't an issue; black was.

BTW, snaking a garden hose into the woods to drain grey...illegal in most states/locations.

[Morich]

And what does the reduced size of the black tank do for getting more grey space?
The idea of adding a second tiny grey in the space made available is not solving the problem of how to connect them to let us use them. The sizes are the way they are because that is the best space they could find that works for the market they aimed to attract!