Thanks, Dave!
You wrote:

The Durban design should be described as an alternating twin pit UDDT becuase two vaults are used, though not in parallel.

But why do you call it a pit? It is fully lined and is really a vault, with nothing seeping out, or am I wrong?
Thus: "alternating twin vault UDDT" if anything? Which is also often called a "double vault UDDT" and we are back to the normal term.

I am against the term "pit" if it is not a pit... A pit is designed to achieve leaching of liquids.

Perhaps the eThekwini colleagues didn't like UDDTs at first and wanted to coin their "own" name for the same thing?

Elisabeth

muench wrote: Perhaps the eThekwini colleagues didn't like UDDTs at first and wanted to coin their "own" name for the same thing?

Well, we also have to see that the term "UDDT" is around for just a few years, and that discussions of names and definitions have a long tradition in the ecosan-movement. Ah sorry, it's called susan now !

I am not sure exactly when UDDT was started being used. In 2006, when at gtz we wrote the predecesssor to the UDDT technology review, we still called it "dehydration toilets". At that time, that was an attempt to be more specfic than the commonly used terms composting toilet, double vault composting latrines, ecosan toilets etc...

I think it would be a good thing, if the "standard definitions" put down in the Compendium are increasingly being used by everyone. But as the whole topic is so dynamic (e.g. think TPS), not sure if that is achievable.

VIP, btw. is age-old (70s) and worldwide understood, compared with all those newer things...

The UDDT review (see www.susana.org/lang-en/library?view=ccbktypeitem&type=2&id=874 ) gives the 3 discussed cases (page 11)

and defines very clearly between them.

In Peru we call the UD VIP ...ECOLET (just to confuse a bit more
I remember that there was another name as well used in Africa.

Yours
Christoph

I'm sorry to go back to kicking this subject.

Is not system 3 in christoph's post (from page 11 of the report) a 'pit' as described by Elisabeth previously - in that it does not seem to have an impermeable base or vault, which seems to me to be the crux of the difference you are saying is widely accepted between 'pit latrines' and 'UDDT vaults'?

Section 2.6.4 specifically talks of "Urine-diverting ventilated improved pit (UD-VIP)".
(edit: see document here: www.susana.org/lang-en/library?view=ccbktypeitem&type=2&id=874 )

Please help me out, am I wrong or not? Is this the same as the UDDT-VIP I referred to before, or is a UDDT different to a UD?

As I said before, I think this is about how you are defining 'toilet'. Elisabeth seems to be suggesting that a Urine Diversion Dry Toilet is the whole system, whereas others are saying that the toilet is the collection mechanism for the system.

I have to say that I really learned something new through this discussion. I was not aware that there are actually examples of pit latrines with urine diversion. I assume that these are not very widespread (the Technology Review says "not well documented").

For Terminology, I'd say UD-VIP would be correct, a VIP latrine with urine diversion.

The DT in UDDT is for dry toilet or dehydration toilet, which is commonly understood (as Elisabeth pointed) out as a lined chamber or another container designed to for collection, drying and easy removal of fecal mater. This is clearly different from a pit, which is basically designed to collect fecal matter without the intention and easy option to remove it from there.
So I'd consider UDDT-VIP not as a correct term, because it mixes two clearly different concepts.

So to summarize, we are talking about 3 technologies here:
- VIP, by far the most widespread toilet type of the three, I think still clearly the most common choice in on-site sanitation
- UDDT, one of the most popular alternatives to VIP or other pit latrines, but still with rather modest distribution globaly
- UD-VIP, a rather exotic solution.

Thanks, Florian, I had not heard that the second D in UDDT was for dehydration, but rather understood it to be a Urine Diversion Dry (as in 'dry rather than flush') Toilet. Which appears to be how the Akvo/Ewag definitions are using the words. I understood the things I was reading by that definition.

I'd like to suggest that someone coin a term for a UDDT (vault) system which does not use words which can be misunderstood or which can be used to describe another system.

I still think that they're being used in different ways.

Florian wrote: I have to say that I really learned something new through
The DT in UDDT is for dry toilet or dehydration toilet, which is commonly understood (as Elisabeth pointed) out as a lined chamber or another container designed to for collection, drying and easy removal of fecal mater. This is clearly different from a pit, which is basically designed to collect fecal matter without the intention and easy option to remove it from there.
So I'd consider UDDT-VIP not as a correct term, because it mixes two clearly different concepts.

I think that the report disagrees with both of you on this point.

The whole of section 2.6.4 reads (edit: in the technology review on UDDTs, see here:
www.susana.org/lang-en/library?view=ccbktypeitem&type=2&id=874 ):

In areas with low water table and with minimal threat of flooding, UDDTs can also be constructed with shallow ventilated pits for faeces collection. Often referred to as Urine-diverting ventilated improved pit (UD-VIP), the configuration presents the simplest form of UDDT systems.

Urine is diverted at the user interface and the faeces are dropped directly into the pit where they undergo a natural mineralisation and composting process.

Diverting urine away from the faeces pit offers a number of advantages over conventional pit latrines. Urine separation reduces odours, provides the opportunity for using urine as fertiliser, slows down the filling rate of the pit and may also reduce the risk of contaminating groundwater resources by minimising the generation of pathogen contaminated leachate.

When the pit becomes full, the super-structure is razed or moved above a new pit. Following the examples of the Arborloo toilet (Morgan, 2004) and the EcoLet in Peru (Hoffmann, 2012), a tree may be planted on top of the decommissioned pit to allow the excreta’s nutrient content to be utilised and the toilet’s former location to be clearly demarcated. As the faeces are left in the ground permanently, it eliminates the need for handling. This model of operation, however, is limited to situations where adequate land is available for digging new pits regularly.

Alternatively, the pit can be emptied after one to two years of continuous composting, in accordance with the Fossa Alterna system described by Morgan (2004) and Tilley et al. (2008). The faecal pathogen content is reduced during the composting process.
As the shallow pit UDDT and its various derivations are not well documented, it is not described further in this publication.

The last paragraph (that I highlighted above) suggests that the document is not distinguishing between UD and UDDT in the way you are suggesting, Florian.

Either the report (Technology review of UDDTs) is wrong, or you and Elisabeth are using terms in a different way to the authors of this section of the report.

Look, there is no authoritity exisiting that prescribes what should be called how. If you like to call something VIP-UDDT, you are completely free to do so. All I try to tell you, is that if you say VIP-UDDT or UDDT-VIP, most people would not really understand what you are talking about.

OK, I was only trying to understand, Florian. I'm saying there is a wide misunderstanding and muddling of terms, and the new report seems to be proving that.

The Durban UD toilets have sealed vaults. We'll have to put the word out that they should not be referred to as twin pit UD toilets, to put an end to the confusion.

Dear Joe,

I think you got me!
That section of the technology review we actually discussed over and over again, and I was somehow never totally satisfied with it.
It is indeed confusing to write:
"As the shallow pit UDDT and its various derivations are not well documented, it is not described further in this publication"
...when earlier I pointed out that UDDTs do not use pits. Will need to consult with the other two authors (Christian and Heike) on how to possibly improve the clarity here, perhaps with an explanatory footnote.

By the way, when I started work at GIZ in 2008, I took over a whole pile of nice documents (thanks to Florian amongst others!). At that time, I "standardised" the abbreviation UDDT to mean: urine diversion dehydration toilet.

When we were writing the technology review, we struggled with that term and in the end Christian convinced me to change my mind. From about 2012 onwards, we started to define UDDT as urine-diverting dry toilet.
We had a debate here on the forum about it in early 2012 which explains the reasons behind this subtle shift for the second D:
forum.susana.org/forum/categories/34-uri...eview-of-uddtsq#1255

I reckon all of the practitioners out there are laughing about us "academic" people right now who are arguing about the meaning of the second D...

But I agree with Joe (and Florian) that this mess of terminology is annoying. We can all do our bit to be very clear on terms in our publications and to help newcomers in understanding what we are on about more quickly.

Elisabeth

It seems to me that the simplest solution is to describe interventions by what they are - eg a urine diversion toilet leading into a sealed vault or a dry toilet to a pit latrine.

Does it matter? It seems to me there are more advantages to having urine diversion than not, and more advantages to having a closed vault than pit, so having a urine diversion vault system is probably better than all the other options. Even so, without secondary treatment, none of them are likely to produce sanitised sludge..