i think the smarter solution is moving down a level where possible:
e.g. agriculture → greywater (agro is a huge water drain 
)
human consumption → drinkwater
quite possibly, I can envision 2 water circuits in certain “high-pain-areas”:
drinkwater for drinking
greywater for flushing toilets, etc…
my WAG is a huge % of human consumption of water is actually never consumed, but flushed down the toilet …
That would still come up short of needs in any given area. Not all water used winds up in the waste system – anything used to water plants whether agricultural or otherwise, as well as sweat and exhalate and I’m sure probably other things I’m not thinking of, isn’t going to wind up in any waste water collection.
(The bad reason: people saying Yucck! Every drop of water you drink has been through various beings’ digestive systems. Lots of times.)
Whether that’s a bright idea depends on a) how clean the greywater is, including of all sorts of contaminants most people don’t think of when they think of sewage b) what the crop is (for multiple factors: some crops are more sensitive to things than others; some crops while not much bothered themselves by particular contaminants tend to concentrate them into what then becomes food; and you don’t want greywater on crops to be eaten raw, if it’ll contact the edible portion.)
In many areas that’s definitely an issue.
The International Space Station recycles 98% of the water on the station (sweat, pee, exhalate…everything). Remarkable really.
Or read Dune and about Stillsuits for a sci-fi take on it. 
True. But setting up an Earthside municipality to do that seems really unlikely to happen. You’d have to seal the place under a dome (or put everybody in stillsuits and seal all surfaces, no plants, no any creature that can’t wear a stillsuit. You might have to invent the stillsuits first.)
– if what you’re commenting on is just that people in some circumstances knowingly drink purified human wastewater: yup, that can happen.
This but other points taken too.
Anyone pulling drinking water out of the Rio Grande is drinking other people’s sewage. I remember visiting a wastewater treatment plant in El Paso and they said the water they were putting back in was cleaner than what was getting pulled out.
Well, in the USA, afaik, there are no plans to use desalination water for irrigation. Mostly for human consumption.
How Is Desalination Different From Water Reclamation? | IDE Tech.
It is a complicated issue-
In summary, reuse is more energy-efficient than seawater desalination but poses other treatment challenges. It requires more complex – i.e., more expensive – technologies have greater potential for scaling and biofouling than seawater and have higher maintenance costs.
https://www.sciencedirect.com/science/article/abs/pii/S0301479708000637
But apparently it is cheaper-
How do potable reuse costs compare to seawater desalination? The cost of treatment depends on many localized factors. The costs discussed here include both annualized capital costs and operation and maintenance costs, including energy. Costs for advanced water treatment, including Reverse Osmosis, which is needed for direct potable reuse, range between $0.45 and $0.75 /m3. Costs are lower for advance water treatment without reverse Osmosis, ranging from $0.32/m3 to $0.55/m3. Costs for desalination of seawater for large facilities varies from $0.50/m3 to $1.80/m3, dependent upon energy cost and location. So the cost analysis would often weigh towards potable reuse, though handling of concentrates or managing the buffer could tip the balance the other way.
Let’s take a look at energy consumption. An advanced water treatment facility requires .95 kWh/m3, whereas the state of the art desalination plants require about 3.3 kWh/m3 . The energy required for potable reuse is significantly lower than for desalination, and the carbon footprint of desalination is three times higher.
So the issue is- public perception. But of course we already drink “toilet water”. Just cycled many times.
You don’t have to go to space. Orange County, CA has had “toilet to tap” for almost a decade.
From the article the OP linked to:
The researchers estimate that if the system is scaled up to the size of a small suitcase, it could produce about 4 to 6 liters of drinking water per hour and last several years before requiring replacement parts. At this scale and performance, the system could produce drinking water at a rate and price that is cheaper than tap water.
Scaling up to produce 6 or 7 litres an hour with the size of a small suitcase, so how much water does LA consume every day? I think we are talking about one or ten million suitcasehours.
This article has been commented in media in Germany, Spain, France and here, so I must commend the authors for their public relations and marketing. But I am not convinced that investing in this method is a good idea.
The same page links to (scroll down):
Oct. 14th, 2020
Feb. 6th, 2020
Feb. 14th, 2020
It seems news MIT edu likes this subject.
Are the developers intending to supply LA and similar places, or are they intending to supply individual households and small villages which currently have no good access to potable water?
A system useless for the first might be quite useful for the second.
'Zactly. The “suitcase” device seems suited to being a per-household unit sufficient for making enough potable water per 24-hour day to support a few people drinking & cooking & a small amount of washing up.
Assuming of course that household had immediate access to seawater.
Moving beyond novel desalinators …
One of the things that may be different in the future in general is the tradeoff between centralized and decentralized provision of anything / everything.
Nobody would think to put a coal-fired steam plant electrical generator in every back yard. Those are huge things you build one of for a city or region & put out in the boonies. But for solar, it may be collectively more efficient to put panels on every building rather than a big panel farm out in the boonies.
Likewise we think of potable water supply as something naturally done by a central plant making fully potable water out of either river water, waste water, or salt water, then delivering that everywhere via pipes. For other tech in other environments potable water supply be better handled by each household making their own in a decentralized fashion.
We used to think of the phone system as fully centralized. The landline system was. Now it’s semi-decentralized with each of us responsible for providing & moving our end-terminal wherever.
Bottom line: It’s important to not assume aspects of a problem or its current solution are immutable; a novel approach may be just the ticket.
They can produce fresh water from 3.5 wt % saline at 3.82 kg.m-2.h-1 at 1 kW.m-2. Assuming a generous average solar irradiance of 300 W.m-2 and linear scaling, I get <30 kg (<8 gallons) per square meter per day.
If supplying all of LA Department of Water and Power’s 435 million gallons per day, that’s about 20 square miles.
Lots of on-the-fly unit conversions here so I’d appreciate someone independently checking.
damn - I’d hate to live in the ground-floor-apartment there …
/s
whenever i read phrases like that I feel I get a little bit dumber … as 0 is <30 kg/8 gallons …
so yes I can confirm … its working … I tried it and got nothing from it …
(not dissing the concept, but the “promotion” of it)
Those are upper bounds given the assumptions. Meaning at least 20 square miles needed for LA.
I know of course, but I felt I had to exercise my doggiven right to be a pedantic prique
… we are the SDMB, after all
There is an actual, commercially made vodka that utilizes such a system. I don’t think it’s the same exact system, but Fog Point Vodka is made from San Francisco fog.
Excuse my skepticism, I once invested some money in Aqua Society, must have been around 2002, 2003… great idea: harvest the condensing water from AC instalations. It is a very good idea, pity it did not work. Today all I found about this former start up is dead links and an out of date webpage I linked to.
ETA: For clarity, this is in reply to Broomstick just above.
I understand your reasoning, but if a lot of people generate their own drinking water locally (very good) and dump each the same amount of double-salted water into the loo this is not going to end well downstream. One thing you cannot filter out of waste water is dissolved salt.
This suitcase idea can work for small scale, isolated settlements. If you try to use it in the places that have the biggest problems with safe drinking water today, like the shanty towns around big cities in Africa and South America, I am afraid that this is not going to work. But of course something must be done, at least they are trying. But this, I am afraid, is not it.
Oh, no, I get it - skepticism is often a good thing.
Fog Point Vodka really does incorporate water from San Francisco fog - that does not mean the system is much more than a gimmick, nor does it mean it will scale, or be cost-effective for drinking water rather an alcoholic beverage trying to position itself as artisanal and a luxury
The vodka is indeed a gimmick, and a good one at that. It depends on the scale: some beetles in Namibia and some cacti in the Atacama Desert (the ones with the white hair) harvest just enough water from the air and that is enough for them. Of course, their consumtion is minimal, but it works. A human, unfortunately, requires a lot more water than a cactus or a beetle. But the proof of concept is there in nature. Does it scale? Up to a point, but within limits.
Right!
another smart idea along the same line…
.
… needless to say the company fleeced a lot of people on indigogo and does no longer exist (surprise-surprise: they never could make the product work (basically a peltier element)) … their debacle is probably only being surpassed by Juiceroo and the Holmes lady.
whats even more embarassing: some austrian gov. agency sunk quite some moneys into them as well. …