I have the same arrangement. I actually prefer this arrangement. Why?
A 12 gallon grey-water tank is FAR too small for a camping weekend. Having a separate, smaller discharge enables you to drain the grey tank on the fly several times over a camping trip.
Most popup campers (PUPS) have nothing more than a drain port out the side of the camper. One attaches a short length of hose and captures grey water in a bucket or proprietary container. What you do with it after that depends on your location...another discussion. In a campground, you can tote the grey water to a pit toilet or bathroom and dump it.
Now, if your grey water dumps thru the black-water port and hose, suddenly otherwise innocuous grey water is contaminated by flowing through the black-tank valve and hose. Furthermore, if someone sees you dumping from the black tank port and thru the black water drain hose into a bucket, they would be justifiably concerned. That's no longer grey water. And that's the case even if you adapt the black-tank fitting to a garden hose. The end of that pipe passed sewage.
On a typical 3 or 4 day camping trip, I dump no less than 20 gallons of grey water...and use the bucket tote method to dispose of it. And that still leaves a significant amount in the grey-water tank.
To fully take advantage of your setup, I recommend the following.
- Valtera (or other brand) grey-water tank dump pipe adapter to garden hose.
- About 10 feet of pliable, non-kink garden hose...cut the end of an old hose so long as it doesn't kink easily. Tip: lay it out in the sun to warm up so it lays flat between the dump valve and the bucket.
- 5 gallon bucket...say the one you had with your "low-wall" PUP.
- And to thoroughly clean your black tank and hose, this adapter is terrific. It actually back-flushes the tank (I back-flush 3 or 4 times until the water coming out is absolutely clear).
This goes between your black tank dump valve and your black-water hose. The extra gate valve and garden hose fitting enables you to use fresh-water to thoroughly rinse the black tank AND flush out the black-tank hose. I've been using one for years. Tip: I store mine in 2 1/2 gallon ziplok bag in a cubby on the PUP that I dedicate exclusively to "yukky" stuff.
(Another story, but my PUP has a U-shaped dinette in a slide. Under the bench seats of the dinette is a large, continuous area accessible thru a cabinet door, lifting the seat bench, AND an outside hatch. I added a small plywood partition to divide the lion's share of that "L-shaped" space into storage for pots & pans {accessible thru the interior cabinet door and bench seat} and a small space for the yukky stuff accessible thru the outside hatch. (The other leg of the dinette is occupied by the hot water heater and a bit more interior cabinet space.) I keep the sewer adapter (bagged), the grey-water hose and Valtera adapter, nitrile gloves and some miscellaneous other yukky stuff in that compartment separated from my cooking utensils. Forest River should have added that partition themselves, because there really isn't another good place for the yukky stuff. The black-water dump hose is stored in its own tube under the camper.)
So, in my opinion, you have a vastly superior setup for a PUP that has a pathetically small grey-tank. Without routine grey-water dumping, grey water will back up into your shower, and with the other kind of dump arrangement, you may be forced to go to the dump station or
use a portable black-water storage tank...assuming you don't want neighbors thinking you're dumping poop into a bucket.
The good news is that a 12 gallon black tank is adequate for a couple for at least 5 days. Unlike grey-water, which is often used with reckless abandon, human waste and the tiny amount of water required for an PUP toilet flush do not fill the tank very quickly.
One other suggestion. The fresh tank on most HW-PUPS is pretty small. Mine is about 20 gallons. I supplement with
4 of these 7-gallon reliance jugs...in my tow vehicle (TV). This more than doubles my fresh-water capacity. Even over 5 days, I've never used all 4--even with showers. In many cases, I've "donated" a 7 gallon jug to a neighbor in need.
Why these jugs?
The cap. Buy a couple spare caps. One's a spare, and one is the makings of a fill adapter.
Add a
1/2" to barb plastic adapter, a
hose clamp, and
about 18" of clear plastic hose (buy this stuff at a local hardware store or Home Depot for about $5 total), and you can adapt the jug to very easily pour its contents into the gravity fill for your fresh tank without dumping precious water all over the place (including you) as happens with funnels and rigid plastic pour spouts. Just lift the jug with one hand and stuff the soft plastic hose into the fill port with the other...then lift the jug until empty.
7 gallons of water is kind of heavy...about 60 pounds. You might need two people to manage. Or you could look for a similar jug (cap) with a smaller capacity. My jugs date back to about 2012 with my previous camper.
If you have plenty of water, your grey-water tank will be overwhelmed pretty quickly, but with the Valtera adapter, an old garden hose and a bucket, you can empty your grey tank daily and never worry about running out of capacity.
And, if you're boondocking you can safely water the trees with your grey water knowing that it's not contaminated by the black-tank dump and hose. That comment may spark another discussion about grey-water "safety," but it's just dishwater and shower water, and the soaps are good for the soil.
Last thought on your fresh tank...assuming you use it. It needs additional support. If you drive full, things will fail. My PUP allowed for the modification in the photo. That's just 1/2" galvanized water pipe, two clevis pins, a bit of rubber floor mat, a bit of plywood, and two 1/2" pipe hold-down clamps. The hanging brackets are built into the frame to guide propane pipes and so on. But you could fabricate a mount if you must. Quick and dirty, and it works great. If you look closely, you'll see that my fresh tank is stepped down below the frame supports, so a simple additional cross-member would not be possible.