Composting Toilet & Black Water Tank

[Bucket Traveler]

If a unit has a composting toilet and by their nature there is no need for a black water tank, correct?  Does the factory then not install that tank or do they have two gray water tanks?

[John E Davies]

The black tank and plumbing, including the toilet flush and black tank flush lines, are always installed on the production line, even if they are not needed. A future owner might want to install a regular toilet. Some owners take out the unused parts, but the factory will not do that. There have been many threads here about repurposing those parts…. So far nobody has announced that they turned that empty 18 gallon tank into either grey or fresh water storage.

John Davies

Spokane WA

[Bucket Traveler]

Thanks

[NCeagle]

16 hours ago, John E Davies said:

The black tank and plumbing, including the toilet flush and black tank flush lines, are always installed on the production line, even if they are not needed. A future owner might want to install a regular toilet. Some owners take out the unused parts, but the factory will not do that. There have been many threads here about repurposing those parts…. So far nobody has announced that they turned that empty 18 gallon tank into either grey or fresh water storage.

John Davies

Spokane WA

The black tank is only a 15 gallon tank.  I opened a ticket and was told it's a "misprint" in the manual.  Maybe the older Ollies have an 18 gallon tank, but I doubt it based on the response I got.

I have been using the 15 gallon black tank as a temporary storage for grey water.  It's a manual process of pumping 15 gallons of grey water from the outlet in the back using a pump to push the water into the black tank with the flush port.  It's working great so far and has saved us from having to carry around one of those "totes" on wheels I see other campers towing / dragging to the dump stations.  There's a post about my solution somewhere on this forum.  Sometimes I can't even use search to find my own posts though.  😉 

[topgun2]

NCeagle - 

One "easy" way to find all of your posts is to click on your avatar.  When your page opens, look for a white box on the right side of the screen that says "See My Activity" and click on it.

Bill

[trekhard]

John how do you get the "grey" water that's in the black tank (now storage) back out then?  Say you wanted to use that for a shower?  

[trekhard]

Bucket Traveler, I was told that RVIA requires a black tank to be installed even if you have a composting toilet.  I did not verify this.  

[NCeagle]

3 hours ago, trekhard said:

John how do you get the "grey" water that's in the black tank (now storage) back out then?  Say you wanted to use that for a shower?  

Hi trekhard, I'd never consider reuse of the grey water in that manner.  I simply keep the grey water in the black tank until the whole trailer is at the dump station and then you can open both valves (grey and black) to empty everything.  Putting 15 gallons of grey water in the black tank gives us about 2 extra days without having to empty the tanks (which is a lot of work if your in the middle of your stay).  Hope this makes sense.

[trekhard]

Oh, now I understand. I thought you meant as a separate clean water source.  😁

[trekhard]

I was reading your post when quite tired! 

[AuthorSP]

On 6/6/2021 at 5:04 PM, NCeagle said:

The black tank is only a 15 gallon tank.  I opened a ticket and was told it's a "misprint" in the manual.  Maybe the older Ollies have an 18 gallon tank, but I doubt it based on the response I got.

I have been using the 15 gallon black tank as a temporary storage for grey water.  It's a manual process of pumping 15 gallons of grey water from the outlet in the back using a pump to push the water into the black tank with the flush port.  It's working great so far and has saved us from having to carry around one of those "totes" on wheels I see other campers towing / dragging to the dump stations.  There's a post about my solution somewhere on this forum.  Sometimes I can't even use search to find my own posts though.  😉 

Good info, Thanks!

 

[AuthorSP]

On a side note, I've seen some TT makers use a combined grey/black tank. Is there a downside to this? Especially in the case of a composting option, it seems having one bigger tank would be a nice option.

[SeaDawg]

On 6/28/2021 at 10:47 AM, AuthorSP said:

On a side note, I've seen some TT makers use a combined grey/black tank. Is there a downside to this? Especially in the case of a composting option, it seems having one bigger tank would be a nice option.

Most trailers that have a combined grey and black are very small, and one tank is all there is space for. The now defunct Airstream Nest had only a small combined grey/black. It was originally designed for a cassette toilet, but market seemed to demand a regular rv toilet.

 

 

[Fritz]

Better to have them separate, IMHO.  There are often more options for emptying the gray-water tank when plumbed separately from the black-water tank.  Some users will rely on public facilities for extending black-water tank capacity; you may have options for emptying the gray-water tank without going to the dump station (e.g,. bucket to drain, etc).  

[Mike and Carol]

On 6/28/2021 at 11:07 AM, SeaDawg said:

Most trailers that have a combined grey and black are very small, and one tank is all there is space for. The now defunct Airstream Nest had only a small combined grey/black, but it was originally designed for a cassette toilet, but market seemed to demand a regular rv toilet.

A combined gray/black would be a no go.  I’m okay with the Oliver fresh and gray tanks but I sure wish the black was bigger than the advertised 18 gallons.  It’s the limiting factor for our boondocking time.  Mike

[Cameron]

Wouldn't it be possible to fill the black tank with fresh water via the exterior rinse port and then drain it as needed with a clean hose for non-potable use?

[John E Davies]

11 minutes ago, mywinnemucca said:

Wouldn't it be possible to fill the black tank with fresh water via the exterior rinse port and then drain it as needed with a clean hose for non-potable use?

You would have to remove and cap the big 3” tank  drain under the front dinette seat on an LE2, and add a separate drain line. the existing setup combines both black and grey lines to a common outlet, so the contents intermix. There is no way to get “clean” water out of the black tank via the outside port. But you also have to remove/ cap the black tank vent and install an overflow port and hose, to separate the systems completely.

If you were going to go to all that trouble it would be simple enough to install a 1/2” pex line to the fresh tank, with an easily accessible ball valve, to gravity drain into an empty fresh tank.

John Davies

Spokane WA

[Skye]

On 6/5/2021 at 7:36 PM, Bucket Traveler said:

If a unit has a composting toilet and by their nature there is no need for a black water tank, correct?  Does the factory then not install that tank or do they have two gray water tanks?

I am assuming that the black water tank still exists but is unused. I have seen folks post videos about how they did a diy thing where they directed liquid waste into the black water tank instead of the provided plastic container. I am not a diy kind of person.  Can anyone direct me to how/where I can find people that can do that for me?

[ScubaRx]

On 7/26/2021 at 4:59 PM, Skye said:

I am assuming that the black water tank still exists but is unused. I have seen folks post videos about how they did a diy thing where they directed liquid waste into the black water tank instead of the provided plastic container. I am not a diy kind of person.  Can anyone direct me to how/where I can find people that can do that for me?

I've read posts in which composting toilet folks said it would be nice if "...they [could] directed liquid waste into the black water tank instead of the provided plastic container..." I've never read a post that someone said they'd actually done it, although if I had that toilet, I would do it. It doesn't like brain surgery.

[SeaDawg]

I've seen several posts by people on airforums who've done that, but not here. One installed it so it was reversible. 

Though urine is 99 per cent sterile, it will def "stink" if kept in a tank, in the heat for days or weeks on end.

If I were going to do that, I'd probably also see if you (or Oliver)  could plumb the bathroom sink to the black tank. Lots of rvs do this, as it's a short run. It would add some grey tank capacity for showers, and dilute the urine in the tank a bit.

https://www.airforums.com/forums/f44/anyone-out-there-connect-their-composting-toilet-to-a-gray-or-black-tank-for-urine-187621.html

You'll probably find some sob brand youtubes, which could be helpful,  as most rvs mount the toilet directly above the black tank.

[SeaDawg]

Btw, at least one waterless toilet manufacturer sells a kit to connect urine disposal to a collection tank. (Separret). The 9215 villa would not fit in an Ollie bathroom, as it's quite large. The new Separret Tiny would, I think, quite easily. Separret has its own issues,,as it uses a rather puny fan to "dry" solid waste and paper, no composting medium. Both require a fairly large vent tube, (though smaller in the Tiny) which would look odd in the bath, and could quite possibly annoy your camping neighbors with the "aroma."

But, looking at their technical drawings and installation guide might give you some ideas.

 

[John E Davies]

10 hours ago, SeaDawg said:

Though urine is 99 per cent sterile, it will def "stink" if kept in a tank, in the heat for days or weeks on end.

If I were going to do that, I'd probably also see if you (or Oliver)  could plumb the bathroom sink to the black tank. Lots of rvs do this, as it's a short run. It would add some grey tank capacity for showers, and dilute the urine in the tank a bit.

I agree that 100% pee will be a big problem. It is super easy to clean a portable tank, I let mine soak overnight  at the end of the season with hot water and some of the old style discontinued Cascade dish detergent (now sold as Fryer Boil Out). The yellow hard crusty deposits vanish. I guess you could clean a permanently installed black tank and the plumbing going from the toilet to it with the same method.

However there is a strong possibility that this design would screw up the tank dump valve quickly by wrecking the seals because of those hard deposits. Lots of grey water from the sink would definitely help, along with some mineral oil or (expensive) valve lube. BTW we never use the sink in the head, other than to add water to the toilet media every now and then and to shower with, we do everything else from the galley one.

We welcome Ollie pioneers, do the mod, report back here and let us know how it works after a couple of camping seasons. 😃

John Davies

Spokane WA

[Mike and Carol]

We always add a capful Calgon water softener in the black tank after each dump along with a laundry detergent pod.  Hopefully it’s keeping our seals in good shape.  Mike