3 or 2 tanks?

[FawnaFox]

I've always wondered why do most RV's and conversions have a Black, Grey and Fresh tank. Is it some kind of standard? Or is it simply black water tanks are more expensive to empty... because I'd like to simplify my system as much as possible and run only 2 tanks, fresh and waste.. Is there a reason I should not or should do that. I also will have limited space for 3 tanks, which is why i'd prefer 2, as my bus has a side mounted fuel tank and AC components in the back, leaving me with limited space for 3 tanks, but 2 would fit comfortably. I wouldn't mind a slightly higher dump fee but if it's drastic I'll reconsider...

 

[skoontz]

I've been thinking the same thing for my build, namely using a 100 gallon fresh tank and a single 100 gallon waste tank. Please note that these are just my thoughts. I have not actually done it yet, and would still love to hear from those that have. Here are my considerations:

From what I understand, in some spots, you can dump the gray tank onto the ground. However I don't think this will help my case, as I would probably just run out of fresh water about the same time as my waste tank(s) fill up. I don't plan on boondocking for prolonged periods, and am not planning on ways to harvest or bring fresh water to my bus. Since I would be taking my bus somewhere to get water, I should be able to also dump all waste tanks.

Having separate tanks would provide some baffling, reducing the effects of liquid sloshing.

The last one I can think of is if repair is needed, smaller tanks are easier to handle. This one really give me pause, as a 100 gallon tank of waste would not be a fun time for maintenance.

On the other hand, I see some advantages to having a single waste tank. Since it would have more liquid, it should avoid the dreaded poop pyramid, and should drain out better. It would also be cheaper (for the same capacity) and easier to build in my case.

 

[nikitis]

Pondering this question. I don't really know the answer either, however my thoughts go to mixtures in the tank. If you put a lot of dirty water with different bacterias in the black tank with #1 and #2 materials, does it create more expansive gases if even more wet?

If it is a problem I think it would be related to that.

 

[FawnaFox]

Pondering this question. I don't really know the answer either, however my thoughts go to mixtures in the tank. If you put a lot of dirty water with different bacterias in the black tank with #1 and #2 materials, does it create more expansive gases if even more wet?

If it is a problem I think it would be related to that.

If there is a problem of expansive gasses, I could find the pressure rating of the tank and put a relief valve on it.. wouldn't smell the best but it's better then exploding turd tank..

 

[turf]

a single waste tank is fine.
out west it is rare to find a place that will let you dump water on the ground so you need to use the waste dump anyway.
every waste tank needs a vent. some fixtures are self venting, like a an rv toilet. but to prevent any exploding turds, run a vent. rvs dont move as big of slugs of water as a household, so the 1 1/2" vent you see on house are very oversized for its purpose.
the longer and straighter the drop into the tank, the better for sanitary reasons.
i and many others run a single waste tank.

 

[nikitis]

If there is a problem of expansive gasses, I could find the pressure rating of the tank and put a relief valve on it.. wouldn't smell the best but it's better then exploding turd tank..

That'd make for a great movie scene. "He was driving down the highway and then heard a HUGE POW! which made him swerve and almost wreck. Narrily avoiding calamity, shortly afterwards, a smell arose, so strong it made him go unconscious, and caused a 20 car pile up. Not from other cars running into the crashed bus, but from cars slipping off of the road after sliding on the huge pile of feces that came from the exploded black tank."

 

[FawnaFox]

I think i came to my conclusion, Im going to use a 40 gallon black water tank that I found on Amazon (here's the link for anyone who's curious https://www.amazon.com/RecPro-Holdi...ocphy=9012102&hvtargid=pla-2281435179018&th=1 ) It has a more compact design, 40 gallon fresh water tank as well. I don't plan on staying disconnected from waste and water service for an extended period of time, so a smaller set of tanks will be fine. I plan on using a 40 gallon barrel or the such.

 

[desrtdog]

Just curious - why not go with a composting toilet?…or the diaper genie type? Then you only need 2 tanks = less space required and no risk of fecal discharges…

 

[TaliaDPerkins]

If there is a problem of expansive gasses, I could find the pressure rating of the tank and put a relief valve on it.. wouldn't smell the best but it's better then exploding turd tank..

Just like any sewerage system, your grey and black tanks should have standpipes to screened U fittings (so they open downwards) which vent them.

For that matter, the potable water tankage must also have a vent . . . probably at the opposite corner of the bus from the other tank vents.

 

[FawnaFox]

Just curious - why not go with a composting toilet?…or the diaper genie type? Then you only need 2 tanks = less space required and no risk of fecal discharges…

My bathroom space is already extremely limited, I have a specific toilet in mind that one of my friends recommended. Although a bag toilet might work.. but the toilet I'm getting has a sprayer built in, which i wanted.

 

[Cheezewhiz]

it's health related.

Black water, ie human waste, has pathogens in it that will happily live inside a human and make them sick enough to actually die. The blue chemical toilet water kills these, but like everything it isn't 100%

Grey water is dramatically less likely to have stuff in it that will make you actually sick. 'Food' poisoning, sure, but not cholera. Diphtheria. Etcetera.

Untreated at all, black water is gross, sure, but grey water WILL make you puke. Even though the black water is actually more hazardous.

All that said, I've never seen a place that didn't just dump it all into one sewer hole, as the sewage facilities process it all the same

 

[turf]

the USA is set up to dispose of liquid waste. its always assumed to be human. dump stations are common and yes, it all goes it the same hole. many free waste dumps are marked by road signs, but most truck stops, like loves or pilot also have them.

the choice to forgo a black waste tank baffles my mind. composting may be a choice, but that doesnt mean its a good choice.

 

[Meathead]

Everybody has a waste dump story. Everybody! I did my best to avoid this. I started out with a TinyJohn poop burner potty. I ended up throwing it out of my Edoor right into a dumpster in Port St Joe FL. Too many problems. I had a natures head toilet shipped in two days later. Not my first choice but it was easy to retrofit on the road as neither unit required tanks.

Four years later. We do two weeks in winter and usually a 3 month summer trip. We have gotten used to the composting potty. I take every opportunity to use facilities at Walmart, campgrounds, truck stops,
Buc-ees! . This saves room. I clean out about every two weeks and replace with new coconut brick material.

Meh…Works pretty well. I could add tanks, sure, but then I would collect black tank stories. There is a reason they say to wear gloves and full face protection when dumping waste.

As always, just my humble opinion.

OH, I recommend that you watch Robin Williams movie “RV”.

Dave

 

[shorthair-SKO]

With 2 waste tanks it's normal to dump the black first then the grey which rinses the waste hose to minimize clean up.

 

[turf]

the more you do it the easier/cleaner it is. its personal habits/equipment and not the system. at its worst, there is nothing the hose wont wash down the drain.
i drain my tank and then hook up a hose and flush it twice. here is a vid of the second flush.

fresh as a dasiy

 

[TaliaDPerkins]

the more you do it the easier/cleaner it is. its personal habits/equipment and not the system. at its worst, there is nothing the hose wont wash down the drain.
i drain my tank and then hook up a hose and flush it twice. here is a vid of the second flush.

fresh as a dasiy

That video is apparently marked private . . .

 

[Mat7783]

I've always wondered why do most RV's and conversions have a Black, Grey and Fresh tank. Is it some kind of standard? Or is it simply black water tanks are more expensive to empty... because I'd like to simplify my system as much as possible and run only 2 tanks, fresh and waste.. Is there a reason I should not or should do that. I also will have limited space for 3 tanks, which is why i'd prefer 2, as my bus has a side mounted fuel tank and AC components in the back, leaving me with limited space for 3 tanks, but 2 would fit comfortably. I wouldn't mind a slightly higher dump fee but if it's drastic I'll reconsider...

Freshwater tank and grey water tank for wastewater from sink shower etc.compost toilet eliminates blackwater tank for sewage waste.

 

[turf]

thank you, i think its fixed.

my point is its a easy clean process.

 

[Mat7783]

Freshwater tank and grey water tank for wastewater from sink shower etc.compost toilet eliminates blackwater tank for sewage waste.

 

[nikitis]

the more you do it the easier/cleaner it is. its personal habits/equipment and not the system. at its worst, there is nothing the hose wont wash down the drain.
i drain my tank and then hook up a hose and flush it twice. here is a vid of the second flush.

fresh as a dasiy

Interesting. so you put a water hose to shoot water inwards to help flush it out? Seems like a genius idea.