hi all,

Pour-flush connected to septic is also common in Tanzania, Kenya and Zambia, but we noted during our sanitation survey in Moshi/Tanzania that more and more house owners tend to leave the septic out and drain directly into the soak-away which so turns into a soak-pit.

A problem of the pour-flush connected to a septic, I see not so much with the amount of water required for the 'flush' of the faeces to the septic. That should be about the same quantity as for flushing to a pit as the distance, the pipe diameter and the slope could be the same. But I could imagine a problem in the septic because the solids are more likely to compact more and faster with the little flush water which will make the emptying by vacuum truck more difficult. Possibly the septic should be filled with water before putting it to use avoiding the fast compacting of the solids. I don't know, will it help, any comments or experiences? When I recently repaired my septic, I actually first filled it with water before putting it back to use to avoid such settling problems.

Connecting pour flush to sewers, I would not rely so much on it being a 'combined' sewer, i.e. transporting sewage and surface run-off. This technology should be avoided by all means as it increases costs (of larger diameter pipes) considerably and still leads to problems when the surface run-off surpasses the capacity of the treatment works and then the surplus run-off (mixed with sewage) is lead directly to the surface water by-passing the treatment works.

I can imagine pour-flush working on sewers where they represent only a limited percentage of all connections, i.e. 25% pour flush connections, 75% full flush connections. This is, because the 'pour-flush use' may also reflect that the plot/household produces less grey-water (having no water connection on the plot) and which then is 'missing' in the sewer for flushing the faeces. Only full-flush connections in combination with grey-water will ensure sufficient flush water in the sewer. Otherwise the faeces will settle in the sewer too easily.

Because of this reason I would also not recommend the construction of sewers in low-income/high density areas if not the majority of customers has water house connections: otherwise the water consumption going into the sewer may be too low to ensure safe flow. We have that problem in the 'renovated' towns of East Germany (the ex-DDR) where new sewer systems were constructed after reunification with the assumption of population increase. But the opposite happened, towns lost inhabitants and now the utilities need to flush fresh water into their sewers ensuring the safe flow of the faeces.

ciao
Hajo

muench wrote: Interesting what you said about pour flush latrine. I think I have only ever seen the pour flush interface being connected to a pit, not do a sewer or septic tank. Would that small amount of flush water even work if it was connected to a sewer?

Pour-flush connected to a septic tank is very common in the Philippines. Of course this requires a bit more flush water, so nothing that would work in a dry area I guess.

Same for sewer connection, that would probably work, but the transport in the sewer-pipes is then the problem. In mixed sewers that also transport storm-water (and reasonably frequent rainfall events), it should not be a huge issue though. I would expect these sewers to smell quite badly in a dry-spell though...

Hi Hajo,
Thanks for clarifying/solving your own riddle! Isn't it amazing that so many of the terms that we use on a daily basis are ill-defined or mean different things for different people? One always has to ask "what do you mean exactly?"...

Interesting what you said about pour flush latrine. I think I have only ever seen the pour flush interface being connected to a pit, not do a sewer or septic tank. Would that small amount of flush water even work if it was connected to a sewer?

By the way in South Africa there is the company Envirosan promoting the EaziFlush: a sitting version of a pour flush toilet - presumably connected to "anything" (pit, septic tank or sewer) (?):
forum.susana.org/forum/categories/low-fl...virosan-south-africa

And in Wikipedia we have the following text on pour flush pit latrines:
en.wikipedia.org/wiki/Pit_latrine#Pour-flush_pit_latrine

Pour-flush pit latrine

Pour-flush pit latrine schematic showing squatting pan with water seal
In a pour-flush pit latrine, a squatting or pedestal toilet with a water seal (U-trap or siphon) is used over one or two offset pits. Therefore, these types of toilets do require water for flushing but otherwise have many of the same characteristics as simple pit latrines. For this reason they are subsumed under the term "pit latrine". The fecal sludge that is removed from the full pits of twin-pit pour-flush pit latrines is somewhat safer to handle and reuse than the fecal sludge from single pit pour-flush latrines. However, significant health risks for the workers who are emptying the pits remain in either case.

An alternative to U-trap or siphon designs is to incorporate a counter-weighted trap door mechanism that provides an air-tight water seal in the closed position.[23] Addition of a small amount of water (generally less than 500 ml) overcomes the counterweight and allows the fecal matter to enter the pit.[24] The devices are sold under the name of "SaTo pan" for as little as $1.85 USD and more than 800,000 of them have been installed worldwide since introduction in 2013.[25]

Greetings,
Elisabeth

A riddle:

A recent survey carried out by LWSC shows that 90% of Lusaka residents use on-site sanitation facilities, consisting of septic tanks (22%), pour flush latrines (10%), improved pit latrines (50%), and traditional latrines (8%). Only 9% of households are connected to a sewer and the remaining 1% defecate in the open. (total = 100%)

Who finds the fault?
Unfortunately the winner cannot win a prize money but only fame...


I think I withdraw my 'riddle' because I have to correct my own understanding of the term 'pour flush latrine'. I was of the opinion that the term covers any pour flush toilet whether connected to septic, sewer or pit and therefore should not be in this 'statistic'. Discussions with colleagues have convinced me that 'pour flush latrine' is a 'pour flush interface' connected only to a 'latrine pit containment'. Pour flush connected to septic fall under 'septic', those connected to sewer fall under 'sewer'. Sorry for any confusion caused, my error!


ciao
Hajo

Dear all,
Elisabeth, I feel you got entangled a bit in your own arguments, let me try and help...

‘Toilet’ can mean (1) for what we sit on, (2) the whole package e.g. "composting toilet", (3) the room, as also indicated by en.wikipedia.org/wiki/Toilet_(disambiguation) . You just have to make clear what you talk of because we will never be able to reduce it to one interpretation.

We need to introduce a new term ‘(user) interface’ when we want to make clear that we only talk of the ‘thing we sit on’ (and not of the room or the substructure = containment) and defining whether it flushes or not.

'Squatting toilet’ should never be the answer to the question ‘what pedestal is it?’ A pedestal is something upright, supporting something else (see all English dictionaries).

The Compendium can call it ‘dry toilet’ or ‘non-flush toilet’ or ‘non-flush user interface’. The first could be the short term once you are sure everybody knows what you talk of, the second the explanation if you want to make sure everybody understands it the same way and the third is the very technical description.

'Urine-diverting dry toilet’ is correct (although originally the second ‘D’ was ‘de-hydrating’) because ‘toilet’ is equal ‘user interface’ is equal ‘what we sit on’ (see (1) above).

I would like us to return ‘translating’ UDDT as ‘urine-diversion de-hydrating toilet’ because the UDDT is a ‘dry toilet’ not because of de-hydrating the faeces but because of not using a flush. Like a compost toilet is a dry toilet (if it does not use a flush) but the faeces are not dry/dried... and a pit latrine is a dry toilet (if it does not use pour flush and water seal) even when the pit is wet from urine, grey-water and/or ground-water. For 'dry' not the containment matters but the interface. And to explain this we need the different terms 'interface' and 'containment' and cannot call it 'toilet' only.

Ciao
Hajo

Dear all,

I was thinking how to reply to Hajo's message and then Dorothee wrote something very similar to what I was going to write! Thank you. I think indeed a lot of confusion stems from the word "toilet". Colloquially, we use the word "toilet" for so many things: (1) for what we sit on, (2) the whole package e.g. "composting toilet", (3) the room (in Wikipedia there is a separate article for that: en.wikipedia.org/wiki/Toilet_(room) )

Then there are even more uses for the term "toilet", see here the disambiguation page:
en.wikipedia.org/wiki/Toilet_(disambiguation)

The Compendium had the idea of using a term of "user interface". I can see the logic behind it but I don't think it has cottoned on that much. After all, the Compendium has been out since 2008 (or?) and yet the term "user interface" is not widely used. Outside of WASH circles it is used even less for toilets. Most people only know it with respect to computing: en.wikipedia.org/wiki/User_interface

I think more common is to simply say: "what kind of pedestal is it? Is it a pedestal or a squatting toilet?", rather than saying "what is the user interface?".

Also, even in the Compendium itself, they didn't stick to their own convention. Rather than calling it "dry toilet", they should have called it "Non-flush user interface". This is the schematic that goes with "dry toilet" in the Compendium:


Source: ecompendium.sswm.info/sanitation-technol...-toilet?group_code=u

Even more confusing is that they call this a UDDT:


Source: ecompendium.sswm.info/sanitation-technol...et-uddt?group_code=u

In my opinion they should not even used the word "toilet" here (going by their logic) but calling it "urine-diverting non-flush user interface".

Anyhow, yesterday, after reading Lukas' response and after thinking more about it, I did quite an overhaul of the Wikipedia dry toilet page. Please take another look and tell me if it's good like this:
en.wikipedia.org/wiki/Dry_toilet

I've tried to make it clear that there is the Compendium definition on the one hand; and then colloquial uses of the term on the other hand.

Terminology [edit | edit source]
One important source states that the term "dry toilet" should only refer to the "user interface" and not the subsequent storage and treatment steps.[1] However, in the WASH sector, the term "dry toilet" is still used differently by different people. It often includes also the storage and treatment steps. For example, it is common that the term "dry toilet" is used to refer specifically to a urine-diverting dry toilet or a composting toilet.[3][4][5]

People also use the term to refer to a pit latrine without a water seal even though the pit of a pit latrine is not usually dry. The pit can become very wet because urine mixes with feces in the pit and drainage might be limited.[citation needed] Also, groundwater or surface water can also get into the pit in the event of heavy rains or flooding. Sometimes households even discard greywater (from showering) into the same pit.[citation needed]

Some publications use the term "dry sanitation" to denote a system that includes dry toilets (in particular urine-diverting dry toilets) connected to a system to manage the excreta.[3][5] However, this term is not in widespread use nowadays, and might rather be replaced with "non sewer-based sanitation" or "non-sewered sanitation" (see also fecal sludge management).[citation needed]

I think it's great when the forum discussion leads to improved content on Wikipedia articles, e.g. because it makes me realise what is confusing. I always have the problem though that I should not write what I think is correct but I should write about what certain publications have said, i.e. everything should have a reference. But this reference does not always exist.... So if you can help with the citations needed, please go ahead. Or write a publication which we can later cite on Wikipedia!

Regards,
Elisabeth

Dear Elisabeth

Thank you for starting this discussion.
I appreciate you efforts of getting the wikipedia pages "right". However, even though the "compendium" is only one source (so is wikipedia), it makes to my opinion sense that we as "experts" agree (and then commit) to certain terms in order NOT to create any further confusion.
The functional groups of the compendium are a systematic way of describing a very broad range of different types of options. This is what is needed for a clear definition even though it might seems technocratic and not very handy when talking to people with different background. However, I think the "compendium" does not contradict any other ("more useful") terms such as "pit latrine" - In the opposite: it allows to systematically define those (pit latrine = dry toilet + single pit).
I think the confusion arises from the term "toilet". In the compendium "toilet" is used to define the user interface only. However, in practice this term is often used to describe both, the upperstructure (user interface) and understructure (pit, composting chamber, or similar). But to call it "dry user interface" and "urine diverting user interface", etc. would make it even more difficult for lay people to understand what we talk about. The user interface is what the user sees and what he will probably be most interested in - toilet is what the user understand best when describing this "place". However, the definition of a toilet as being only the user interface will probably be very difficult if not impossible to mainstream because this would somehow forbid terms like composting toilet. In order not to splitting hairs however, I would go ahead with your the suggestion of Elisabeth:

One source defines dry toilet as xxx. In common use though, other definitions also still exist side by side (provide some example references for where dry toilet is used to mean composting toilet, for example)."

Moreover I also think that it could be useful to create a wikipedia page on "non-sewered sanitation (systems)" which could then again be linked to the paragraph about "dry sanitation" in the "sanitation" page.

Cheers, Dorothee

Hi Elisabeth,

Whilst I really think the Compendium is super, I have always felt that distinction for "user interface" separate to "storage etc." is quite artificial and does not "work" all that well outside of academic circles.

I am sorry, but I disagree considerably. For me the distinction between 'interface' and containment' is very relevant. And it must be made by professionals not only by academics and must be brought to the attention of people 'outside of academic circles'. Why?

• A full flush toilet/interface can be connected to a 1) sewer or 2) septic tank.
• A pour flush toilet/interface can be connected to a 1) sewer, 2) septic tank, 3) latrine pit
• A drop hole/interface can be connected to a 1) latrine pit, 2) cesspit, 3) septic tank (called 'aqua privy)

For any of the above interfaces the service chain (emptying, transport, treatment, reuse) will look quite different depending on which containment the interface is connected to.

I have seen surveys by respectable consultants who showed in the legend of the sanitation map definitions like 'pour flush' and 'septic tank' on the same level which does not make any sense because the pour flush can feed into 3 different containments and a septic tank can be fed from 3 different interfaces. Thus, a pour flush toilet can feed into a septic tank. How do you mark it on the map: as pour flush or as septic tank? It is both: a pour flush 'interface' and a septic tank 'containment'.

We did a sanitation survey of 46,000 households in Moshi and we noted how important it was that we differentiated between 'interface' ('toilet', as the people commonly say because that is what they see, they use, they know) and 'containment' which is mostly hidden but the more relevant part of the service chain for 'us professionals' because it determines possible ways of emptying, transport, treatment and reuse.

Just for clarification: 'interface' is for me the piece you sit or squat on PLUS the respective flushing mechanism (full flush, pour flush, SATO 'flush', no flush)

Curious, to hear other comments,
ciao
Hajo

P.S. This PhD thesis from 2010 about the Erdos project in China with UDDTs also used the term "dry sanitation" and "dry toilets" to denote UDDTs:
www.susana.org/en/knowledge-hub/resource...library/details/1172
Flores, A. (2010). Towards sustainable sanitation: evaluating the sustainability of resource-oriented sanitation. PhD Thesis, University of Cambridge, UK

I am not saying this is good. I am just collecting evidence that the term "dry sanitation" and "dry toilets" is used by folks when they actually mean UDDTs.

Dear Lukas,

Thanks for your detailed response! I absolutely agree with you that it is worrysome that many different uses of these words still prevail and that it would be great to streamline them. This is what I am trying to do with this forum thread and with Wikipedia articles.

Regarding the Compendium it is a great piece of work. But I was always missing a consultative process at the time. It feels a bit like it fell from the sky and Eawag decided "this is how it's meant to be!". There is no way of knowing much about the thought processes behind it, except for asking you... I find the advantage with Wikipedia is that it tries to build consensus and anyone can see how it develops by looking at the history or the talk page of the article.

Whilst I really think the Compendium is super, I have always felt that distinction for "user interface" separate to "storage etc." is quite artificial and does not "work" all that well outside of academic circles.

I actually disagree with your statement that:

A toilet is a “user interface”, where the user has to “go”. The user does not usually care if that is connected to a single pit or VIP, composting chamber or dehydration vault, septic tank or sewer

Of course the user does notice whether it is connected to a pit (pit latrine) or to a septic tank/sewer - quite a big difference in user experience, I would say. It is impossible to make the user interface look & feel the same. It already starts with the fact that a pit latrine always has to be separated from the rooms of the house.

About your question:

@Elisabeth: what leads you to the conclusion that
When people speak of "dry sanitation" they usually mean sanitation systems with dry toilets with urine diversion, in particular the urine-diverting dry toilet (UDDT).?
In your experience, is the term “dry sanitation” even used much at all?

I see it used ocasionally. Most notably perhaps in this paper by Christoph Platzer where he used dry sanitation to mean UDDTs:
www.susana.org/en/knowledge-hub/resource.../library/details/961
(I think it's a good paper; I will ask Christoph if he's still a proponent of this term or not)

If we can all agree on "dropping" the term dry sanitation, I think that would be good. But I think we should make it explicit, not implicit. In the Compendium it is "implicit" - you just don't mention the term. In Wikipedia we can state why the term is no longer that commonly used (although it is hard to find a reference for such a statement! Quoting this forum discussion is not good enough).

And I disagree with you on this statement:

it is also not correct to say: “Pit latrines without a water seal also fall under the category "dry toilet".”

According to the Compendium logic: yes. In your logic, already the term "pit latrine" is a combination of toilet + storage. That might make sense in the Compendium logic but I would say it doesn't make sense for "everyday use" where we call a pit latrine a toilet. And if we call it a toilet we should be allowed to call it a "non-flush toilet" or a "dry toilet".

But we might be splitting hairs here. Let's try to get it clear in the Wikipedia article on "dry toilets". Is there anything you would change?:
en.wikipedia.org/wiki/Dry_toilet

Note I don't think it would be right to make this Wikipedia article into a 1:1 copy of what the Compendium says. For me, the Compendium is just one source of information here. Thus I would perhaps say "One source defines dry toilet as xxx. In common use though, other definitions also still exist side by side (provide some example references for where dry toilet is used to mean composting toilet, for example)."
This way, we explain the whole story not just what the Compendium recommends.

Regards,
Elisabeth

Hi Hajo

Yes - a dry toilet is simply a toilet without flush, or we could also say no-flush toilet.
The SATO pan is a special form of a pour-flush toilet (without S-trap). It does depend on water and is therefore not a dry toilet.

Lukas

hi Lukas,

I appreciate that you agree that there is not need for the term 'dry sanitation'.

Thank you for clarifying that the Compendium refers the term 'dry toilet' only to the interface, i.e. 'dry toilet' is a toilet without any flush.

If you can make everybody understanding it this way it is acceptable. Many users, administrators, politicians would not exactly know what it is, but everybody will understand 'toilet without flush'. Therefore I prefer to stick to the latter term.

What about the SATO pan which uses minimal water (0.5L/'flush') to clean the pan and ensure the seal of the flap? Dry toilet or not dry toilet?

ciao
Hajo