Has anyone converted a cassette toilet to black water tank?

[Davydd]

Originally Posted by booster

Although some would disagree, there really is not a real good reason to have a black tank as long as the grey tank has adequate capacity for both uses. Using a macerating toilet, maybe with a small pedestal tank under it so in batches would prechop everything so would likely work just fine. No gravity to the tank as it would pumped, so a small 1" line would be able to be used.

I kind of agree with you as I will have a macerating toilet in my new van since I will a back toilet behind the back axle and still have a black tank in front of the axle that I need to get over. BTW, that's why you see so many composting and cassette toilets at rear van toilets.

However, on a Sprinter at least that I have studied, you can't get the total capacity in one single tank. I'm talking my current combined 44 gallons of black and grey tanks. I do like the follow up rinsing flush with grey water. I totally enclosed at both ends it may not make much of a difference but in examining my hose before grey tank flushings I see a lot of dingleberries that I think would build up with time if I don't follow with the soapy grey water. That's why I like separate tanks. The black is fully enclosed and vented. The grey has areas that can vent to the cabin if not maintained with water in the traps. Grey is bad enough but black would be much worse.

[ks@yvr]

Ah the proverbial plus and minuses of black, cassette, composting and wagg bags. Personally we have had both black and cassette and I prefer the cassette toilets. In this part if the country it has been harder to find dump facilities for black tanks and some of the dump fees charged have increased to $20 or more. Some campgrounds will only let registered guests use their dump facilities and if you agree to pay their overnight fee they still will not let you dump. We had this happen to us last summer where we were on an island for a month that had only 2 dump stations and neither would let anyone other than their guests dump. The only option was to leave the island by ferry and return. A macerator pump would have been an option into a vault toilet would have worked but at the moment since we did not have one it wasn’t an option. We have gone to cassette with our new build because it gives us more options. James (fitrv) little invention that connects to a short Camco adapter hose for a dump station is not a crazy option imho.

[Paul the Gardens]

Originally Posted by GeorgeRa

He admitted his negativity towards cassettes, I will give him a credit for it. With his 180 degree turn now he wants to sell his invention which adds a hose to a cassette defeating the cassette benefit of no hose, no hose cleaning, no hose storage.

An invention is a solution to a problem, good luck selling a solution to a none existing problem.

I was thinking the same, and while watching the FitRV dumping his cassette into the sewer look out, why didn’t he introduced the 6 inches pipe of the cassette into the sewer look out ? This is as easy those cassette system are well made and one can position the pipe just over the sewer and slowly pour the waste while holding the cassette and introduce the cassette’s pipe into the sewer. How simple can that be ?

[ks@yvr]

Amazon carries this adapter that James from FitRV emailed me that makes the job of dumping a cassette easier with his prototype screw on thingy.

https://www.amazon.ca/dp/B07FJFZPHL/...v_ov_lig_dp_it

[GeorgeRa]

Originally Posted by ks@yvr

Amazon carries this adapter that James from FitRV emailed me that makes the job of dumping a cassette easier with his prototype screw on thingy.

https://www.amazon.ca/dp/B07FJFZPHL/...v_ov_lig_dp_it

I am not sure how this gadget would work, the drain insert end would need to be inserted before dumping, just don’t know how this would be possible, the cassette would have to be in the draining position before insertion?

Perhaps adding a miniature macerator into a cassette, powered by poop bacteria organic batteries, would help dumping cassettes.

Ideal scenario would be from Star Trek times, “beam poop down” Scotty.

[rboegh]

Originally Posted by Bert M

I stumbled into the opportunity to drive a new 20' Winnebago with a layout I liked (4 seats up front). The new vans with front wheel drive are no different than driving a minivan - extremely easy compared to the 20 year Roadtrek I had been driving. I liked it except for the cassette toilet. Has anyone converted a cassette toilet to a blackwater tank? I would like to know the challenges of fitting one on and if there are any outfits that do this.

I don't want this thread to digress into defending cassette toilets. They are not for everyone. I only want to know if anyone has converted a cassette toilet to a blackwater tank on any class B RV.

We purchased a Solis this fall, after owning a Hymer - Carado with a macerator and black tank, and was wondering the same..... could we install a macerator toilet and pipe/pump over to the gray tank and use that for duel purpose, gray and black water?? I will say I was not real keen on the cassette as well, but have found it to not be as bad to use as I thought.... we can get 4-5 days out of it for 3 people if I also use restrooms while traveling... wife and daughter will not.

Interested to follow and hear if this conversion could be done, I have not, but will call a reliable RV service person I know and ask same. I will let you know what I hear and approx cost....

By the way, we love the Solis 59PX layout and simplicity of systems use over as you can guess the Hymer..... Great rig!

[Davydd]

I don't see much downside to a cassette toilet other than weight and frequency of dumping. At my age I am starting to have difficulty in handling 50 lb. salt bags and my wife more so. At 6 gallons that means tending to them three times as much as my 18 gallon black tank.

That Camco sewer hose would make it similar to gravity dumping a black tank but is there followup with grey water to semi clean out the hose? When we used to gravity dump the much larger grey dump used to clean the hose so we seldom never needed to rinse with the water hose. How do you rinse at a vault toilet? In macerating dumping for a black tank the 1-1/2" hose is fully enclosed and capped at both ends and simply has to be put away.

[avanti]

The other problem with the cassettes is that they rely on the integrity of the large gasket seal between the cassette and the toilet in order to prevent odor. That is why most of the good ones come with exhaust fans. My experience is limited, but we had a constant low-level odor problem with a non-fan unit, and that was with using chemicals, which I never find necessary with a plumbed toilet. I consider the fan a band-aid solution. Others have reported no odor issues, but our experience was a significant turn-off for us. Lots of people seem to think that RV toilet odor is inevitable, but know this not to be true.

[booster]

Originally Posted by rboegh

We purchased a Solis this fall, after owning a Hymer - Carado with a macerator and black tank, and was wondering the same..... could we install a macerator toilet and pipe/pump over to the gray tank and use that for duel purpose, gray and black water?? I will say I was not real keen on the cassette as well, but have found it to not be as bad to use as I thought.... we can get 4-5 days out of it for 3 people if I also use restrooms while traveling... wife and daughter will not.

Interested to follow and hear if this conversion could be done, I have not, but will call a reliable RV service person I know and ask same. I will let you know what I hear and approx cost....

By the way, we love the Solis 59PX layout and simplicity of systems use over as you can guess the Hymer..... Great rig!

This option was mentioned earlier in this discussion, and IMO, it is probably worth investigating to see the practicality of doing it on the van in question.


One big thing will be cost as it is a one off type thing, I suspect, so installers will probably not be inexpensive in their quotes, especially since the grey tank might need to be removed to add the connection to it, and as was also mentioned earlier, good venting would be needed to be confirmed. If it is a DIY, then the labor is much cheaper as long as it within the ability of the owner and they don't have to buy a bunch of new tools (which for some of us might be considered a plus ).

[GeorgeRa]

Originally Posted by Davydd

I don't see much downside to a cassette toilet other than weight and frequency of dumping. At my age I am starting to have difficulty in handling 50 lb. salt bags and my wife………………………...

I agree, frequency of dumping is a key differentiator between a black tank and a cassette. For me an important benefit of cassette is easy cleaning. We just came back from the camping and one dump, one wash with a cap of detergent followed by rinses makes my cassette crystal clean, it took 5 minutes.

Originally Posted by avanti

The other problem with the cassettes is that they rely on the integrity of the large gasket seal between the cassette and the toilet in order to prevent odor. That is why most of the good ones come with exhaust fans. My experience is limited, but we had a constant low-level odor problem with a non-fan unit, and that was with using chemicals, which I never find necessary with a plumbed toilet. I consider the fan a band-aid solution. Others have reported no odor issues, but our experience was a significant turn-off for us. Lots of people seem to think that RV toilet odor is inevitable, but know this not to be true.

I have a very popular Thetford 402C and my experience is very different.
A standalone 402 Cassette is fully sealed in any position, upright, upside down, or sideways. It has to be sealed to transport it to a dump. I never had a leaking cassette since installation in 2013.

Cassette has the following areas which can leak:
a. Main valve, it is a rotating blade with 2 motions, a rotary motion and an upright sealing motion. During rotation there is not much pressure between the blade and cassette seal, in the final few degree of closing the blade snaps with force upwards pressurizing the blade against the seal. If this blade is not snapped to a completely closure cassette’s gas will escape to living space. Upon removal this valve will be automatically shut closed even if it wasn’t completely closed. An additional slider provides safety so during transportation cassette main seal seals on both ends, seal to the slider and seal to valve’s blade.
b. Drain cap
c. Vacuum breaker valve
d. Automatic vent valve located on the bottom of the cassette. It vents the upper air space in the cassette and it opens automatically during cassette insertion. If this vent is routed to the roof there is no difference between venting cassettes or black tanks. Electrically powered vents could be used as well eliminating a need for sometimes difficult routing to the roof. I don’t think electric vent is a band aid, just a different approach to venting.
e. There are other seals used for assembly sealing.

Toilet bowl:
There is a seal between the cassette and the bowl. This seal can be tested by monitoring water level in the bowl, water drain will indicate a leak.

Any system, black or cassette seals can leak, but in my experience for the last 8 years none did and I had no problems with odor I did however had a past problem with the black tank.

[Boxster1971]

Thanks all for contributing to this thread. It has been very informative on cassette toilets - which I'll probably have in my next van.

[Redfish]

I understand that this is not a cassette versus Blackwater discussion but may I say that one should not make a decision on scrapping a cassette system unless they have used or they understand how a cassette toilet functions with an electric extraction fan system. I have three RVs. One is an older Winnebago at home in Canada with a black water tank that I have used for 20 years. I have a Hymer in Europe and another in New Zealand both with cassette toilets equipped with SOG extraction fan systems. For a detailed understanding of the SOG I suggest YouTube “what is a SOG”.

https://m.youtube.com/watch?v=oggqyC3jQGE

I have more than 11 years experience using these two systems approximately six months per year. I understand that thetford has an electric extraction fan system for some or all of their cassettes. I have yet to meet anyone who has had one installed and I have never had any experience with that system. There are many advantages of using the SOG extraction system but in my opinion the most valuable advantages are no need to use chemicals. No chemical or toilet smells inside the vehicle and no chemicals being dumped into a system. When using the toilet and the slide valve is open, the extraction fan operates ensuring that there are no odors. Yeah I know what you’re thinking. Yes NO odors inside. No chemical perfume and no waste odor. Even farts get extracted. It takes me less than three minutes to dump the cassette and there is no black hose to deal with. If I going to continue using the toilet I would just give it a very quick rinse and spray the slide valve area with silicone and stick it back in and rehook up the SOG. No messing with chemicals. No need for fussy cleaning unless you are going to store it. When the toilet is not in use and the slide valve is closed and the fan is off, the cassette is still open to the outside through a charcoal filter. There is therefore no positive or negative pressure in the tank, therefore no upper splash when you open the slide valve. Some or all thetford systems have a pressure release valve that opens when you slide the cassette in. That is not the dumpIng vent. This must be deactivated as the SOG system is permanently vented to the exterior through the charcoal filter.
We get 3 to 4 days between dumping. You could extend it to six days if you pee outside. Whether that would work for you or not it’s really the only thing to decide.

[Gulfvet]

For me it is about also having access to New England seashore camping with our class B 4x4. Cassette toilets are NOT allowed. You MUST have a black water tank for waste.

[Punkinhead]

Originally Posted by Gulfvet

For me it is about also having access to New England seashore camping with our class B 4x4. Cassette toilets are NOT allowed. You MUST have a black water tank for waste.

We just ran into that trying to reserve a spot at a private campground in Wichita, KS. We have a composting toilet and they told us there's a city ordinance requiring permanent black tanks. I started googling to see how common this is and found some spots in California and some long term BLM camping areas require black tanks. I wonder if these are just regulations out of tune with modern RVs or if they have a legitimate reason.

[GeorgeRa]

Originally Posted by Punkinhead

We just ran into that trying to reserve a spot at a private campground in Wichita, KS. We have a composting toilet and they told us there's a city ordinance requiring permanent black tanks. I started googling to see how common this is and found some spots in California and some long term BLM camping areas require black tanks. I wonder if these are just regulations out of tune with modern RVs or if they have a legitimate reason.

Cassette toilet has a very negative opinion in NA propagated often on different RV forums including this one or by RV “experts”. General opinion is that they stink, they leak, give brown noses, emptying is repugnant vs just about perfect black tanks. No doubts that this negative view can reach decision makers to accept or reject cassettes on their campgrounds.

It is certainly possible to epoxy a cassette in its housing and connect a permanent drain line to it. A questionable success would be a 5 gal. black tank for the sake of these few campgrounds not allowing cassettes.
In our travels we had no issue with cassette.

[avanti]

To answer OP's question:

If you can fit one of these in your bathroom:

https://www.amazon.com/Icon-22-1-Bot.../dp/B0058SQFRG

Then replacing your cassette toilet with a black tank system is a pretty easy project. Cut a drain hole in the floor, add this tank, frame it in, and put a standard low-profile toilet on top of it. Add a dump pipe and valve underneath and you are done.

If I were faced with this project, I would certainly do it. My experience is limited (but so is that of most of the supporters), but my most serious problem when I used one was that it smelled (in an otherwise pristine rig). It smelled a lot. It smelled even though I religiously used the little pack of chemicals after every dump, as per the manufacturer's instructions. It was pretty gross.

As best as I can tell, the folks who say they don't smell mostly have units with exhaust fans to maintain negative pressure under the seal. Mine did not. Now, I do believe that if you have such a fan and are willing to run it all the time, you will probably be fine. But my preference is for a system that doesn't need such a fan.

[GeorgeRa]

Originally Posted by avanti

To answer OP's question:

If you can fit one of these in your bathroom:

https://www.amazon.com/Icon-22-1-Bot.../dp/B0058SQFRG

Then replacing your cassette toilet with a black tank system is a pretty easy project. Cut a drain hole in the floor, add this tank, frame it in, and put a standard low-profile toilet on top of it. Add a dump pipe and valve underneath and you are done.

If I were faced with this project, I would certainly do it. My experience is limited (but so is that of most of the supporters), but my most serious problem when I used one was that it smelled (in an otherwise pristine rig). It smelled a lot. It smelled even though I religiously used the little pack of chemicals after every dump, as per the manufacturer's instructions. It was pretty gross.

As best as I can tell, the folks who say they don't smell mostly have units with exhaust fans to maintain negative pressure under the seal. Mine did not. Now, I do believe that if you have such a fan and are willing to run it all the time, you will probably be fine. But my preference is for a system that doesn't need such a fan.

Cassette can be vented verbatim the same is black tank without a fan with roof penetration.

[avanti]

Originally Posted by GeorgeRa

Cassette can be vented verbatim the same is black tank without a fan with roof penetration.

I assume they have to be vented (although I could be wrong). I can't swear that mine was passively vented, but my guess is that it was. If so, it wasn't enough. A non-powered vent will not produce negative pressure unless there is wind.

EDIT: I just looked as some photos of the rig and I could not see a roof vent, so perhaps there wasn't one. Having one would certainly help while under way, but not always while parked.

[Boxster1971]

Originally Posted by Gulfvet

For me it is about also having access to New England seashore camping with our class B 4x4. Cassette toilets are NOT allowed. You MUST have a black water tank for waste.

This is also true at many California state campgrounds.

Edit: I made a mistake on this comment the restrictions I read about were at National Park at Cape Cod. I got my coasts mixed up.

[GeorgeRa]

Originally Posted by avanti

I assume they have to be vented (although I could be wrong). I can't swear that mine was passively vented, but my guess is that it was. If so, it wasn't enough. A non-powered vent will not produce negative pressure unless there is wind.

EDIT: I just looked as some photos of the rig and I could not see a roof vent, so perhaps there wasn't one. Having one would certainly help while under way, but not always while parked.

With a roof exhaust black tank is very similar to cassette regarding odor. If black tank toilet blade/ball valve or cassette valve are not sealed they will generate odor. The only toilet which would be immune to odor is a marine style macerator toilet. Did you consider if your bad experience with cassette is due to its failing leaking seals?

Regarding roof vent, as long air above the waste has higher temperature than ambient (dumps tend to be warm) there is going to be some draft. A well design roof vent can pull exhaust gases via venturi, so for some percentage of time passive vent can be a “self-powered” one.