Grey to Black Transfer Pump * Genius or Crazy

[Durango RV]

Thought occurred to me that we fill the grey tank MUCH faster than the black. But for some reason the Grey & Black tanks are the same size?!

So, what if I installed a transfer pump with a one-way check valve to move grey water into the black tank?

As I see it the benefits are:
> Extended boon-docking as the grey water can also fill the black tank.
>> It's relatively easy to add more fresh water from a jerry can.
> Better wash out of the black tank with the extra grey water fluid.

Other than the cost of the parts and the hassle to connect the tanks is there something I'm missing?

[bobbecky]

Install a Valterra twist on valve on the discharge fitting and then open both the grey and black drain valves with the twist on valve closed and the tanks should balance levels to each other.

[fjr vfr]

Don't like the idea of both tank valves being open together. I don't want the chance for black water to be flowing up into my grey tank.
In many boon docking areas there is no restriction for discharging grey water onto the ground.
It is frustrating on many trailers, (like mine) the tanks are the same size.
when we camp in places without hookups we practice several conservative measures with the grey water. First we use paper plates, (not plastic) and paper bowels. When we do need to wash out dishes we use paper towels and wipe them mostly clean so as to use little water to finish the job. We also use a bowel for rinsing out dishes and silverware. We can then just toss that water out. Lastly we use campground showers.
Works for us.

[RickV]

Or you could just get a tote.

[Lee]

Hi,

I exclusively Boon-dock and (I may catch flack for this but) my grey water goes onto the forest floor.

[JRTJH]

Originally Posted by bobbecky

Install a Valterra twist on valve on the discharge fitting and then open both the grey and black drain valves with the twist on valve closed and the tanks should balance levels to each other.

It's not "just that simple" if you consider the size of the valves in most trailers. The black tank valves are always 3". The gray tank valves in most trailers, are 1.5". It's "sort of easy to push black tank contents into the gray tank if you open both valves (as in your suggestion).

The problem is once those black tank contents "settle to the bottom of the gray tank", how are you going to get them out with the smaller valve, slower flow speed as the tank empties and no flush system to augment that "slow flow" ???

It's not a good idea to "augment black tank size by "flowing/equalizing the black and gray tanks. Doing so will not only contaminate your gray tanks and fill them with hard to remove solids, it will, as posted above, eliminate the ability to dump "gray tank contents" on the ground in areas where that practice is still permitted.

The "main issue" (IMO) is trying to get the solids out of the gray tank once they "migrate there"......

[JRTJH]

Originally Posted by Lee

Hi,

I exclusively Boon-dock and (I may catch flack for this but) my grey water goes onto the forest floor.

That's a common practice in many areas and, where it's permitted, a great way to extend a camping trip.

The "problem for many" is the food contents in the galley tank. If dumped on the ground, near the trailer, those food contents will attract flies and could be a source of "aroma" that attracts other critters, some twice the size of humans...

"Sneaking a dump" in bear country may not be the "greatest idea".... Sort of like chumming on a deep sea fishing trip

[Gkri]

Originally Posted by Durango RV

Thought occurred to me that we fill the grey tank MUCH faster than the black. But for some reason the Grey & Black tanks are the same size?!

So, what if I installed a transfer pump with a one-way check valve to move grey water into the black tank?

As I see it the benefits are:
> Extended boon-docking as the grey water can also fill the black tank.
>> It's relatively easy to add more fresh water from a jerry can.
> Better wash out of the black tank with the extra grey water fluid.

Other than the cost of the parts and the hassle to connect the tanks is there something I'm missing?

We use a plastic tub in the sink for dishwashing and dump that into the black tank to conserve space in the grey tank. As a bonus, the dish soap helps keep the black tank clean.

[Gkri]

Originally Posted by Gkri

We use a plastic tub in the sink for dishwashing and dump that into the black tank to conserve space in the grey tank. As a bonus, the dish soap helps keep the black tank clean.

i mean to say dump the dishwater into the toilet...

[Durango RV]

Lots of good discussion here. That's what I like about these forums.

"Balancing" between tanks using the connections between the valves doesn't sound like something I'd like to try. At best I'd get half the grey tank emptied with all the potential issues folks have mentioned.

As fjr vfr said we limit water usage to extend the number of days we can boondock. Fewer showers, disposable plates and so on.

This past summer we were camping at Yellowstone. To extend the time before having to dump I emptied 5 gallons of grey water at a time into a bucket and dumped it down the toilet. It allowed us to go several more days before having to dump. The transfer pump idea would accomplish this with the flick of a switch.

[travelin texans]

If adding the valve to the dump end then, if equipped with 2 grey tanks, open both grey tanks to equalize this will add capacity as typically the galley tank is the last to fill, so with that valve you double the bath grey capacity & no harmful cross contamination.

By adding this cap to that valve you can attach a dedicated hose & run the grey water deeper into the woods so not attracting critters or insects right at your door.
Personally would not connect black & grey together either as then technically you'd have 2 black tanks with s##t in both. Pumping grey contents into the black would be OK, but I would not go to trouble or expense to alter the plumbing to add a permanent pump. Dumping dish water down the toilet would achieve the same result & cost nothing to accomplish other than a few steps.

[Durango RV]

We only have one grey tank but that cap you showed caused me to have an epiphany.

What if I installed one of those caps. Then ran a short hose between the cap and the black tank wash port with an in-line drill powered pump to move the water?



I'd have my transfer pump the easy peasey way with minimal cost.

[travelin texans]

Originally Posted by Durango RV

We only have one grey tank but that cap you showed caused me to have an epiphany.

What if I installed one of those caps. Then ran a short hose between the cap and the black tank wash port with an in-line drill powered pump to move the water?

Attachment 42510

I'd have my transfer pump the easy peasey way with minimal cost.

The issue I foresee with that plan is that if any food particles from the kitchen sink or hair/soap scum from the bath go thru the pump they'd plug up the spray nozzle in the black tank then other than a hose thru the toilet you'd have no black tank rinse.
You didn't post what rv you have, unless it's a very small one, it's unusual to not have 2 grey tanks.

[JRTJH]

In addition to Danny's comments, if you do get "grease/food particles" into the black tank flush system, assuming you still have your anti-siphon valve working properly, it likely won't be working at all after you destroy that little rubber diaphragm in it. Once that gets "dried out or stopped up" you might just wind up pumping dishwater into the outside black tank flush connection on the side of the trailer and right out the top of the anti-siphon valve and into the vanity. If your DW is like mine, she won't find the least bit of "humor" in wet, soggy toilet paper and her favorite hair dryer covered in greasy dishwater......

[flybouy]

Originally Posted by fjr vfr

Don't like the idea of both tank valves being open together. I don't want the chance for black water to be flowing up into my grey tank.
In many boon docking areas there is no restriction for discharging grey water onto the ground.
It is frustrating on many trailers, (like mine) the tanks are the same size.
when we camp in places without hookups we practice several conservative measures with the grey water. First we use paper plates, (not plastic) and paper bowels. When we do need to wash out dishes we use paper towels and wipe them mostly clean so as to use little water to finish the job. We also use a bowel for rinsing out dishes and silverware. We can then just toss that water out. Lastly we use campground showers.
Works for us.

Sounds like those paper "bowels" might be prone to causing issues with moving those "bowels". Sorry, couldn't pass that up.

[Durango RV]

Travelin Texan. Hummm. Possibly a screen on the intake side of the pump to stop solids from being fed to the black tank spray nozzles. I realize it may require frequent cleaning but would serve the purpose. BTW, we're just a stones throw away at YPG for the winter.

And yes, it's a relatively small 22' unit - Bullet 220RBI

Holding Tanks:
Number Of Fresh Water Holding Tanks 1
Total Fresh Water Tank Capacity 43.0 gal.
Number Of Gray Water Holding Tanks 1
Total Gray Water Tank Capacity 30.0 gal.
Number Of Black Water Holding Tanks 1
Total Black Water Tank Capacity 30.0 gal.



JRTJH "you might just wind up pumping dishwater into the outside black tank flush connection on the side of the trailer and right out the top of the anti-siphon valve and into the vanity."

Can you explain this to me - like talking to a 5 year old as they say. I get that there is a one way valve between the flush port and the black tank. But there's no connection between the black water system and the vanity. Sinks (kitchen & bath) along with shower feed into the grey tank. Only input to the black tank is from the toilet.

[JRTJH]

Originally Posted by Durango RV

[B]...

JRTJH "you might just wind up pumping dishwater into the outside black tank flush connection on the side of the trailer and right out the top of the anti-siphon valve and into the vanity."

Can you explain this to me - like talking to a 5 year old as they say. I get that there is a one way valve between the flush port and the black tank. But there's no connection between the black water system and the vanity. Sinks (kitchen & bath) along with shower feed into the grey tank. Only input to the black tank is from the toilet.

As for using a "hose washer with a screen" that may stop "chunks" but it won't stop grease or detergents which will destroy the diaphragm in the anti-siphon valve.

There are TWO (not one) connection to the black tank. One, as you indicate, is the toilet. The other is the black tank flush system. It has an "anti-siphon valve" (not a one way valve) to prevent black tank contents from being "siphoned into the community fresh water system". The LOCATION of that anti-siphon valve (the one I discussed) is in the black tank flush line, which in almost all Keystone trailers, is under the vanity. Check your vanity, when you open the door, count the number of PEX lines you see. If there are two (blue/red) they are the hot/cold supply lines to the vanity faucet and YOUR anti-siphon valve is installed somewhere else in the trailer, probably behind the shower faucet area. If there are four, the other two PEX lines are for the black tank anti-siphon valve flush system. Here's are photos of what you'll see:

[Durango RV]

JRTJH You taught me something new today. I checked and there is a anti-siphon valve under the bathroom sink inside the vanity. Thank you for the info.

Well, back to the drawing board!

[JRTJH]

Originally Posted by Durango RV

JRTJH You taught me something new today. I checked and there is a anti-siphon valve under the bathroom sink inside the vanity. Thank you for the info.

Well, back to the drawing board!

That anti-siphon valve is, IMO, the weakest link in the entire RV plumbing system. It won't survive a freeze, it won't survive high pressure or a "jolt" from quickly turning on the water to the flush system, it won't survive storing the trailer in hot weather and it won't survive storing the trailer with the least bit of water in the valve during freezing weather... In other words, "IT WON'T SURVIVE anything but the most careful use and cautious care.....

Many/most of us have simply removed it and bought a "quality brass anti-siphon valve" in the irrigation section of Lowe's or Home Depot, adapted fittings to that "improved valve" or simply removed the valve and built a "L shaped" fitting to replace it and used a "faucet end anti-siphon valve" (also found in the irrigation section of Lowe's or HD.

If you keep the OEM valve in place, the slightest "insult to protecting it" will provide you with a quick way to use every dry towel in your linen cabinet.

But, even with a replacement, more durable valve, you'll still face a buildup of grease and detergent residue on the flush spray head inside the black tank. Stop that valve and the flush system no longer works until you unplug it. That's no easy (or pleasant) task, given what's inside the tank..... YMMV

[travelin texans]

It's sounding like dumping the dishwater down the toilet, from your bowel (should be bowl), is looking like a good plan.
BTW you do, hopefully regularly, dump from bowels & hopefully down the toilet.
Oh yeah! Marshall started it!