Last Thursday I posed the question of how often the water you drink has been pissed by a vertebrate already. If the number is very small, then those who baulk at drinking recycled water have more cause to complain than if the number is very high.
As some commentators to that post pointed out, in reality we are all drinking water that includes some recycled piss: every dam from which we drink has ducks, lizards, and all sorts of animals pissing and shitting in it, so it is already a bit of a myth to think one can drink water that has not been recently mixed with piss. Still, as another comment revealed, many think the idea of copying Singapore and drinking water that is officially recycled sewage is deemed ‘gross’. So the question how often water has been piss in the past still matters for the ‘yuk factor’.
The answer comes from a very simple formula, which requires a few guesstimates as inputs:
Piss ratio = (total water pissed)/(total water) = (total vertebrate biomass ever lived* piss rate)/ (total water) = (average biomass vertebrates * piss rate per year * years of vertebrates) / (total water)
This simple formula thus boils down to 4 inputs for which we can search for good guesstimates.
The amount of water on the planet (total water) is the easiest one because it is the sort of thing geologists and physicists are good at estimating. As this linked article computes, there is around 1.386 billion cubic kilometers of water on the planet. Whilst it is true that this water comes in various forms, that is not relevant for the calculation: since we are considering hundreds of millions of years, it doesn’t matter how much of that water is currently salt, fresh, stored in ice, or whatever: compared to such long time horizons it all circulates pretty fast so there is no problem in taking it all as one blob of water.
I can already say that my best guess for how much water we humans have pissed during our existence is around 800 cubic kilometers, meaning that only one 2-millionth of the atoms in the average water molecule will have been pissed out by a human. So we might be drinking reconstituted piss, but not much is reconstituted human piss.
Now, onto the other three inputs into our crucial equation. What is the average wet biomass of vertebrates? If we take the present as a reasonable guess for how much vertebrate biomass the earth continuously houses, then the answer we can gleam here is around 10% of total animal biomass (zoomass), or in the order of 5 billion tonnes of wet biomass (a lot more than dry biomass which you will often see reported). This includes up to 2 billion tonnes of dry-biomass fish, a little under half a billion tonnes of human, close to a billion tonne of things we might eat that walk on land (cattle and such), and 2 billion other wet biomass. In turn, this is in the order of one thousands of total biomass.
Admittedly, the estimate of 5 billion tonnes of wet vertebrate biomass may be out by a factor of 2 or so, but can easily be an under-estimate since I only found a dry biomass estimate for fish.
Then the next part of the equation: how much does a vertebrate piss per year? Again, this turns out to be a tricky question because only birds and mammals produce concentrated urine like we do. The rest pisses much weaker stuff, though things like fish still produce ammonia and the other normal elements of piss because the basic physiology is not that different between us and a fish. So the process and form of piss is not the same across species but the substances produced by our bodies and eventually excreted somehow are not that dissimilar.
So we need to slightly alter the definition of what we are looking for and think of piss as a ‘human-like’ substance. We can then again take a conservative approach and don’t count the watery piss that fish produce as ‘100% piss’ but rather as a much weaker variety of what we produce. We can then take ourselves as the measure of what a body produces and simply scale up, getting an easier question to start out with: how much do we humans piss in a year? The answer turns out to be that we piss around 1.5 liters per day, or 500 liters per year. Another way to put this is that we piss out 8 to 9 times our weight in wet biomass per year.
Then onto the last unknown, which is the number of years that vertebrates have been around in the abundant form of life we have now. Again, a tough one. The earth is now quite a bit cooler and probably less fertile than it was in the times of the dinosaurs, so the amount of biomass walking around now is probably quite a bit less than it was in the more productive phases of earth, but by the same token for much of the earth’s inhabited history the inhabitants were bacteria and not things with spines. If we concentrate on the period of the vertebrates, the best guess is that fish arose some 500 millions years ago, whilst land was conquered by vertebrates some 380 million years ago. Taking a conservative guess for the total period of time that the volume of vertebrates we have now has been present, this means that the wet vertebrate biomass we have now has occupied earth for around 350 million years.
We can now put the pieces together to compute our piss ratio: 350 million years of 5 billion tonnes of wet vertebrates pissing 8 times their body weight per year equals 14,000 million cubic kilometers of piss. This means the atoms in your average water molecule will have been concentrated piss some 10 times already. And that is a conservative estimate. In the more likely scenario, there would have been more like 10 billion tonnes of vertebrate biomass on average, pissing 10 times their own body weight, living 400 million years, equating to water having been piss around 25 times already.
Perhaps equally interesting I can give some idea how often the water has been piss from a particular group of vertebrates. Starting from the best guess estimate, water has been fish piss some 10 times, mammal piss around twice, and other forms of piss 13 times. Only a trickle has been monkey piss.
As per usual, champagne to all those who thought the answer was ‘often’ (which is all commentators game to give a guess). Unflavoured recycled filtered desalinated naturalised piss for the rest!
That’s what I come to the Trop for: in depth analysis of the big issues.
Wake up Paul. “Yuk factor” isn’t the main problem with drinking human effluent.
“Piss” isn’t the only thing that goes down the loo, unless in your unique world there are two separate sewage systems to handle each component separately. Your comments slide neatly from discussing recycled sewage to discussing “piss”, without making any differentiation.
What part of “contains pathogens” don’t you get? We are NOT talking about trivial “yuk factor” as the primary concern. We are talking about medically recognised pathogens.
Pathogens include things like: typhoid, cholera, hepatitus, salmonella, assorted viruses, amoeba, worms, etc.
A more reasonable question would be how many times has water been ‘piss’ since it last fell as rain.
In the case of Warragamba Dam, much of the water comes from the Wollondilly and Coxes rivers , both of these rivers receive a fair bit of urban and farm contributions – for example a lot of the dog do laid down in southern suburban Katoomba/blackheath and so on ends up in the streams flowing into the dam.
John,
I believe emess had a go at calculating that one in the first post on this. Its a low number, but I would guess it is very dependent on how far downstream it is.
Elise,
of course I am being provocative, but surely that is the only way to truly tackle the ‘yuk factor’. Your question about poo is of course also interesting. Taking the average of a quick web search, we poo 400 grams a day of which around 50% is water, so if we scale this up, the water you consume has actually been vertebrate poo around 4 times.
And of course there is more to the recycling debate than the yuk factor, but it is remarkably strong.
Paul, so poo is 50% water, in your estimation. Which means exactly what, for public health?
What dilution factor do you think is safe?
On what medical evidence?
Paul
I think this ‘piss’ thing is just a red-herring, a rather pointless one at that.
As Elise has succinctly pointed out, the real issue is “how clean is the water you drink”
We all encounter dirty water every day, but we don’t drink it. We all know that rainwater from dams originally fell in the catchment area onto ground, animal droppings, rotting leaves and so on. (Similarly for tank water off roofs)
But so long as it’s clean now we’ll drink it.
How about I create a glass of water that I can absolutely guarantee you has *never* been piss? (I can do this by burning hydrogen in air, collecting the vapour and condensing it – bingo brand spanking new water that never existed in the universe before)
Would you drink it? Of course you would. How about if I add some e-coli to it? They’re invisible, the water looks the same.
Will you drink it now? Of course not.
How about I add a small amount of something to it to make it cloudy? Something safe, like milk. Will you drink it now? Without knowing what’s actually in it? No
I think we all know that for the most part *all* of the water we drink has been contaminated in some way in the past before. But that’s NOT the criteria we use to judge whether it’s drinkable.
What we assess is “how clean is it right now?” What’s happened to in the past is completely irrelevant.
“But so long as it’s clean now we’ll drink it.”
Isn’t part of the point of the post based on the assumption (with rather stronger evidence) that this isn’t true?
Given this, I don’t think it’s pointless at all. Just showing that all water has been piss a number of times (let alone in limited systems where the number of recyclings would be much higher, like central Queesnland) is a reasonable strategy for pointing out the obvious which people don’t want to believe.
Frankly, Paul, this whole thing is bizare. I can’t imagine what caused you to start posting about it.
Your fundamental assumption here, that there’s some kind of irrational “yuk” factor attached to human excreta is just wrong. It’s the entire reason why the western world started building sewage systems, and the entire reason why cholera, for example, is no longer a major killer in the west.
You sound like a bought and paid for corporate lobbyist. If that’s what you are, then good luck to you. Disclose the relationship, then piss off. If you aren’t, then WTF?
Good point SJ
In fact, Paul is making an argument not unrelated to homeopathy. He seems to saying that a large proportion, perhaps a very large proportion, of the population believe – in his estimation – that water retains characteristics of its previous pollutants.
His concern is IMHO a strawman and he appears to be trolling.
You obviously don’t live in Victoria where have a ridiculously expensive desalination plant when vastly cheaper options were rejected based on the “yuck” factor.
“His concern is IMHO a strawman and he appears to be trolling.”
Doesn’t seem like trolling to me. The yuk factor – or disgust – which was once an adaptive response to pee and poop, and other potential sources of pathogens, is a ‘fact’ and it does have a significant effect on the choices we make. People are unaware of this unconscious bias, which means that they are unable to make a rational assessment of the ‘problems’ with recycling water.
SJ, JM,
keep it civil. You obviously do not share my views on the importance of the yuk factor but you are being disrespectful and abusive without actually putting real arguments forward. Your repeated views on pathogens in recycled water implies the recyclers are trying to poison you. If you want to argue that, then argue it politely. I will not tolerate further abusive comments.
Conrad, Julie,
thanks.
Paul
I gave you real and detailed arguments on the previous thread. Recycling treated water outfall is a very expensive undertaking as Singapore has proved.
Since as was pointed out on the previous thread the treatment of water in this way is somewhat similar (reverse osmosis, nanofiltration etc) to desalination, such treatment is likely to be as expensive if not more so than desalination.
More likely more expensive as the solids load in treated water is higher than that of seawater (6% versus 3%), the solids are different in nature – they are suspended rather than dissolved like the salts in seawater. Consequently operational costs would be higher, particularly as salt is easy to manage and control in your filtration plant whereas treated sewage is much more complex.
The yuk factor is not something that the vast majority of people worry about. The real problem is cost.
Oh and another thing – volume.
The amount of water in our sewers is drawfed by the volume of ‘grey’ water (ie. from showers etc) and especially storm water. If you want to save water, start with storm water first.
“The yuk factor is not something that the vast majority of people worry about. ”
JM, just to refresh your memory, try reading: http://www.thechronicle.com.au/news/toowoomba-recycled-water-poll-five-years-later/1066451/ , or indeed any other of the things about Tawoomba at that time. If the weather had not changed, it would have been really interesting to see what would have happened.
You might also want to look up why Melbourne built a desalination plant versus the vastly cheaper recycling plant also (the dams got to less than 25%, which would have been even more exciting than Tawoomba given the population). The answer to that is the same. People don’t like the thought of drinking recycled grey water.
Thanks Conrad, I just read that article you linked to, and noted with interest:
“Five years on, from her home in Tasmania, she stands by her fight to bring recycled water to Toowoomba. Ms Thorley blames the bitter fallout from the referendum on the No campaign, claiming the tactics used by Water Futures’ opponents left the city permanently scarred. “I think Toowoomba was used by Snow Manners, Clive Berghofer and Rosemary Morley and destroyed, literally destroyed.”
Strong words there. Over strong, I would venture. Toowoomba “used…and destroyed”?
Wasn’t there some dispute about the quality of independent assessment of alternatives, and about the real costs of the alternatives? What safeguards were to be put in place?
By the way, if a sewage treatment plant is direct-coupled to the drinking water, does the risk analysis include the cost of cleaning out the total reticulation system, in the event of plant failure releasing pathogens into the system? Aside from the political fallout if people get sick or die?
Perhaps we could just rebrand any medical problems or deaths as the “yuk factor”?
Elise, Toowoomba is the closest supermarket town to the small town in which I live. Toowoomba has recovered – it was not permanently damaged lol – but Di Thorley was right, it was a very emotional and I think underhand, unethical and political campaign. I don’t really know what went down but those blokes she mentions always seem to get what they want regardless of what other less powerful people want.
In my little town, we get our water from a bore and it is a council requirement that every house has a water tank so the issue wasn’t going to affect me much. I wasn’t eligible to vote in the referendum so I didn’t bother to check for myself the facts but there were other problems that people were putting forward as the reasons they were voting no and denying that it was just the yuk factor. Some people from the yes side overdid the ridicule thing and that created more defensiveness. It was quite nasty and indeed a town divided.
According to this article
http://www.theage.com.au/news/national/recycled-water-were-not-that-thirsty/2007/01/06/1167777325058.html
“DRINKING recycled water doesn’t wash with most Australians, with nearly half believing it contains human waste and 70 per cent equating it with purified sewage.”
Disgust is recognised as an important factor in human behaviour but I don’t think it is a very strong ‘instinct’ in humans. It must be able to be socialised out for certain ritual or other reasons. I have read of tribes who do really disgusting things with the dead and decaying flesh is supposed to the be the biggest disgust trigger.
This is an example of the really important type of research done on disgust.
http://www.united-academics.org/magazine/26594/sexually-aroused-women-experience-less-disgust/
Interesting quote:
“DRINKING recycled water doesn’t wash with most Australians, with nearly half believing it contains human waste and 70 per cent equating it with purified sewage.”
You know what? They are absolutely 100% right. Recycled water as delivered out of your bog standard sewage treatment plant DOES contain human waste (and a whole lot more besides). It IS “purifed” sewage.
What comes out of the Singapore plant is something completely different. And it is very expensive to produce. So expensive it is not viable to use as drinking water.
Period. I’m amazed people can’t face clearly stated facts that I have explained at length.
Would not disagree… However a lot of river sourced drinking water contains treated sewage that was put into the river by settlements upstream. (And much also contains wild dog and wild pig poo.) Mostly by the time it gets to the next user it is very dilute and the natural processes of rivers and swamps have reduced the contamination significantly.
Yes John, you’re right to a certain extent. But not entirely.
As I explained on the other thread, the river itself is part of the clean up system. Natural biological processes go to work on the remaining solids and break them down and reprocess them.
This is evident from two things:
1. the river plant life (and subsequently fish etc) is more abundant at a sewage treatment outfall
2. no-one abstracts water from the river until some miles downstream, no-one takes their drinking water from immediately downstream of an outfall. They wait for quite a distance.
Then when water is ultimately abstracted a little chlorination is usually enough to produce potable water.
Now when you examine the situation of Melbourne and Sydney – there are no rivers to provide these natural biological processes downstream of the sewage treatment plants. Both cities are on the sea. There is no “downriver”.
In those cases, the sea provides the necessary biological processes and further treatment.
Short of building a very expensive plant like that in Singapore, using recycled sewage for drinking purposes is logistically, geographically and economically impossible.
JM
Isn’t the osmosis process also something that cannot just be turned on and off ?
On the other hand.
Melbourne has a lot of flat land around it that could( in theory) be used for reed beds and so on . The water (in theory) could be used for parks ,gardens and horticultural purposes ( fruit trees, grapes, fiber plants like hemp and thus reduce net consumption of premier cru water.
I have also read that putting water through underground aquifers is a efficient way of filtering.
And in Sydney, which still gets about 400-500 mills in dry years, requiring every new building to include rainwater storage would be a cheaper way of augmenting storage and reducing the net use of drinking water to flush toilets.
John that is in fact exactly what Weeribee already does. There is quite a lot of farm land around it and they ‘recycle’ about 40% of their water there.
Check Melbourne Water’s website
As for rainwater storage, there is now a thriving industry involved in supplying such tanks to households and others.
See, what gets my goat about this cocktail party meme is that it is usually (always) advanced by people who have no idea of
a.) what the current situation actually is
b.) have little to no knowledge of the processes and constraints involved
Once it’s examined closely the idea evaporates as either:
1. already being done, or
2. impractical or too expensive to be of any use, or
3. dangerous to the public health
But it does make you sound “forward thinking and bold” when expressed in a fact-free environment.
JM
Doing osmosis of sewage in a city that has easy access to seawater is obviously a nonsense.
And it was not the subject of this post.
Putting treated sewage into rivers upstream of dams happens every day .The Coxs river is not at all safe to drink untreated and no bush walker with any brain would go near the streams that flow down from Katoomba … all of that water goes into Sydney drinking water.
JM,
they’re already recycling water from Melbourne’s favourite poo farm on a huge scale, and it isn’t very expensive:
http://www.water.vic.gov.au/initiatives/recycling/werribee
As it happens, I believe almost all of that water is already taken, and whilst I’m not a hydrologist, I can’t see why they couldn’t just take this water and turn it into potable drinking water (it probably already is given they are sticking it on plants) without massive expenses.
I would imagine that things like nitrate/phosphate and salt levels and possible contaminants from ‘backyard’ factories -solvents pigments and the like- would be more of a concern than bio contaminants for the farmers of Werribee
Can we get our definitions right here please.
a.) Paul posed a red herring related to the molecules of water and applied the yuk factor to those molecules alone, ignoring the possibility of pathogens. I think we’ve dealt with this particular canard. What is important is the cleanliness of the water we actually drink. Treated sewage is not clean enough nor safe to drink
b.) ‘recycling’ as used by Melbourne Water does NOT refer to potable water, it refers to irrigation and other non-drinking purposes. Check the webpage I nominated a couple of hours ago. MW define 4 classes of water – A to D – of declining quality. Class A water is defined as non-potable, D is worse and is only suitable for non-food agriculture. They recycle 8 Glitre of Class A. That’s 8 days supply (approx) for Melbourne.
c.) the only place in the world where water is taken directly from a sewage treatment plant and reintroduced into drinking water (albeit only about 1% of it) is in Singapore where it is first processed in a very expensive plant. That plant uses osmosis and microfiltration. Very similar to the desalination plant. A similar plant for sewage would cost a similar amount. There would be little advantage in capital costs and operational costs would probably be higher as sewage is harder to deal with than seawater.
Furthermore the feedstock for such a plant would have to come from the existing Class A water. A Singapore like plant would therefore cost about as much as the desalination plant, and supply only 8 days water a year.
d.) all other water that we drink is reprocessed via the natural environment, either a river, a dam or the sea
So the Singapore approach is a non-starter. Traditional sewage treatment is not good enough to produce potable water. Simple really.
The idea of drinking treated sewage is impractical. Period.
JM, if the cost of creating potable water is so high, how are most cities in places like China (and many other places) creating their water? For example, I’d drink the water used from Werribee any day over anything coming out of almost any Chinese river (indeed raw pee is probably healthier than some rivers). So why isn’t Chinese water costing a fortune?
“Why isn’t Chinese water costing a fortune?”
Maybe it is? Relatively speaking.
Who owns the water treatment plants – private enterprise or Chinese state owned enterprise?
If it were an SOE then possibly cost may not be their primary driver, compared with social and public health imperatives?
Conrad
In traditional circumstances, say the Ganges in India, nobody drinks water from just downstream of an outfall, or if forced they boil it. If they don’t pathogens are rampant and disease widespread.
In the post 18th/19th century framework, sewage treatment plants are used to reduce the toxic load on the river. This water is not fit to drink, however small sips , or even a glass, won’t hurt you. Everyday use will. A certain proportion of it is fit to irrigate crops. Werribee already do this.
This describes the situation in the Thames Valley. No-one drinks water immediately below an outfall. No water is abstracted until a further 10 miles down river. (And even then it is chlorinated before being delivered to taps – but chlorination is a pretty cheap process). So although the residents of London drink water that “has been piss” in the bellies of Reading residents, and Reading residents in turn drink water that has been piss in the bellies of the denizens of Swindon, the river has had its chance to dilute and biologically clean up the residual muck.
(Please note, the residents of Reading and London all know that the water they drink “has been piss” only a short time before. They don’t give it a thought. They know it has been cleaned and is safe. There is no “yuk” factor. Paul’s contention is a fiction, a distraction, and false. The only thing that matters in the mind of any rational person, and indeed millions of real people, is “is it safe”)
Werribee differs little from the Thames Valley plants, but there is no river so we dump it into the sea and let the water cycle do the rest. It comes back to us as rain.
(Someone mentioned towns upstream of the Melbourne dams. Here both the river feeding the dam and the dam itself provide the water life necessary to run the biological processes to clean the residual muck.)
If you’re willing to live on a permanent intake of Werribee water, you’re crazy. You’ll get sick very quickly
However, if you wish to provide Werribee water directly as drinking water, you *could* do it by installing a further filtration plant like NEWater in Singapore.
That hypothetical plant would then put the water through additional stages (refer the section “Process” in the above link):
* microfiltration to remove suspended solids (ie. shit), colloids (ie. smaller particles of shit that won’t settle out under gravity), bacteria, viruses etc
* reverse osmosis to remove heavy metals, nitrates, chlorides, disinfectents, organic solvents (paint thinner etc), pesticides
* ultra violet radiation
Note these last 3 processes are very similar to those proposed for the Wonthaggi desalination plant. They are expensive.
In other words, if you want to make recycled sewage fit to drink you need a plant of similar capital cost and scale to the Wonthaggi plant (for the same volume of water)
IMHO however using these processes to clean sewage is operationally more expensive than cleaning seawater. Seawater is consistent in composition and salt is relatively easy to handle. Sewage is not. It is inconsistent and contains all sorts of things such as illegally dumped chemicals (which often also cause problems in the 18th/19th century technology and sometimes cause the biological processes there to stop functioning). Running a plant like Wonthaggi on sewage feedstock would be more complex and more failure prone.
So take your pick. Do you want to spend your $4 billion on the Wonthaggi plant with low (relatively) operational costs? Or do you want to relocate it to Werribbee and suffer higher operational costs and greater risk of “breakdown” in the plant?
I know what I prefer.
BTW – there is another reason for Melbourne to prefer desalination to sewage recovery. The efficiency of a dam->tap->sewer->plant->tap cycle is not 100%. In a severe drought water usage falls and the amount of water flowing through the sewerage system also falls, so the amount of water recovered would also fall.
ie. just when you need it most, output from your sewage recovery system wouldn’t be there.
Sorry, just to restate that last comment a little more clearly:
* any sewage recovery system will always return less water than was in the dam originally. If the dams are empty a sewage recovery system will only delay the inevitable shortage at the household tap.
* desalination doesn’t suffer from this. The seas are not going to dry up, so the only limit on the water it provides is the capacity of the plant. The feedstock is limitless and you can take as much as you need and/or can pay for.
Hahaha I love this! So you are a genius! I do know the Singapore water recycling plant is quite a success and it’s not too bad an idea. We are, quite literally, pissing away a lot of our water, water which could go into storage and reused. Yuck, I know, but hey, we don’t live in a world where we have a huge storage of clean drinkable water. Even the water you drink now is not exactly fresh from the Alpine mountains or something. They all come from everyone and everywhere, including the piss from Bob of the next block. I suppose in Australia, it can be a good idea we follow the way Singapore has their own self storage of water to tide over (pun not intended) the drier periods. It’s much more important when the human population reaches so high, adding to the world so many flushing toilets, that recycling water becomes not a joke but a worthwhile idea.