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Here's what I'm curious about: how much water is used for every liter of drinking water? It seems clear that a "liter of water", which could be all kinds of pol

Here's what I'm curious about: how much water is used for every liter of drinking water? It seems clear that a "liter of water", which could be all kinds of polluted, is NOT the same as a liter of bottled or tap water. A liter of drinkable water has to undergo some filtration process, etc. and I'd be extremely interested in seeing how much water is used in that process. That would help put the headline's figure in context.

sanxiyn 11y ago
Quick search gives http://www.npr.org/sections/thesalt/2013/10/28/241419373/how-much-water-actually-goes-into-making-a-bottle-of-water http://www.npr.org/sections/thesalt/2013/10/28/241419373/how... which is not very easy to interpret.
- nxzero 11y ago
  That's bottled water, not tap water. My guess is it varies greatly to due the source of the water. At the extreme, I would guess that desalination of saltwater to make it usable for drinking water would likely consume huge amount of water per drink unit of water. Given that it's a pretty obvious question, find it interesting that it is not addressed; reason likely is most reporters do not do investigative journalism, but many will publish as is a story forwarded to them. Lastly, it's very likely some water used was not drinkable to start, reused, etc. - which is to say, it's a complex topic and without a clear question and an understanding of why it is being ask, you'll always get an answer that appears to answer something.
  - arviewer 11y ago
    How would desalination cost water? You vaporize water, catch and cool it back to water, and there you go. The cost here is energy, which varies greatly depending on the sun.
    - nxzero 11y ago
      Unclear how much you know about the topic, but there are a number of ways to desalinate salt water, including just mixing non-toxic saltwater with drinkable freshwater; that said, it requires 31 liters of freshwater to make one liter of saltwater drinkable. Normal saltwater has a salt concentration of 3.5% and to be drinkable that must be reduced to 1000 ppm (parts per million); which is to say, say for 100 liters of saltwater, you'll lose at least 3.5 liters just to reclaim the freshwater itself. Beyond that it'll depend on the system how much additional volume is lost in the desalination process; quick Google finds some systems that lose 20% of the volume per unit processed. Lastly, your reference to energy consumption brings up an example of additional sources of water lose. Water used to cool systems, water used to clean systems, leaks/waste, etc.
      - nxzero 11y ago
        Not that I post for rep, or for that matter care about downvotes, but if you're expressing that the above comment was not of use, on-topic, opinionated, bad tone, etc. - it's not clear why. Please comment so that I might be able to address your concerns. Cheers!
      - arviewer 11y ago
        When you need 31 galles of freshwater to make 1 gallon salt water drinkable, you have 32 gallons of drinkable water. Those 32 gallons are not wasted. When you make one jeans or a t-shirt, you may need many more gallons. You cannot drink that water afterwards, so that totally different.
        nxzero 11y ago
        Reference to using freshwater for desalination has nothing to due with waste, but to make the point that boiling saltwater is only one of many ways to desalinate saltwater.
2muchcoffeeman 11y ago
You'd have to distinguish between potable water and just any water too. https://en.wikipedia.org/wiki/Drinking_water https://en.wikipedia.org/wiki/Drinking_water mentions that Christchurch, NZ has a sufficient supply of pure enough water that no treatment is required. So you could probably build a passive filtration system for a one time cost. It just may not be fast enough to treat enough water if your population is too big.
- ioquatix 11y ago
  I live in Christchurch and I can confirm our water is AWESOME.
  - acveilleux 11y ago
    So's your coffee!
Retric 11y ago
Very little water is lost in municipal water filtration. The largest loss is generally evaporation from dam reservoir which is on the order of 10%. Depening on location temperature, humidity, ect. Don't forget you drink the same water you bathe with. At scale it's producing a lot of water. PS: Now a lot of water is lost after filtration by leaks/breaks in water pipes. But, that's mostly an economic choice as water is really cheap replacing pipes is expensive.
- DougN7 11y ago
  To compare to this article you'd also have to calculate the amount of water used to make the pipes, dig the ditches, create the machinery to dig the ditches (and pro-rate the machinery's life time against the amount of time it's used to dig water pipe trenches), fuel used, etc, etc.
  - Retric 11y ago
    Your scale is off. The city of Philadelphia for example loses 60 million gallons per year to leaks out of 250 million gallons pumped from the river. (excluding leaks at the home and business level estimated at 1trillion gallons per year in the US.) To get anywhere close to similar levels from the article you replacing there entire system every 20 years would need to take 20 * 60m * 340 = 408 Trillion gallons of water.
- logicrook 11y ago
  The point he is making is not reduced to that, it is that you should judge things with the same metrics. I.e. how much water is used for bottled water? For running water? How much harmful chemicals can you find in soft drink, bottled water, tap water? (because running water may be very cost-efficient, but it comes with a price, the dizzying quantity of chlorine you can find inside being one). Just giving one number out of your hat is a dishonest persuasive move (unless everybody already knows the numbers for all the previous questions), precisely because the author knows very well that most people cannot put that number into perspective. This is not a very scientific attitude for something published in a 'scientific' journal.
nixy 11y ago
At home I have a 1:1 ratio. I've got my own well and my own pump, so every liter of water I get out of the well flows out through my tap. I guess you could argue that the electricity needed to work the pump may be produced by means that waste water.
- VLM 11y ago
  The mine that dug the iron that made your pipes contaminated a lot of water. In the vegan world its standard to count every drop of rain that hit the livestock pasture as being used, therefore its fair to count the rain that ran off the factory roof where the pump was manufactured as used. Wells don't dig themselves and although that doesn't happen often, it does take a lot of water to do it, and make the gear to do it, and get the diesel fuel out of the ground and onsite to run the drilling rig. I drink every drop from a can/bottle, usually, but I am a bit wasteful in the kitchen sink and probably only half the tap water is swallowed. Not to mention my dishwasher uses 5 gallons or 10 gallons or whatever small number every time it cycles and washes my drinking cup (so my drinking cup's share is only maybe 1/2 cup of dishwasher cycle water, but, maybe I was only thirsty for 1/2 cup of water leading to 50% efficiency right there). And of course the dishwasher uses electricity (water) and detergent (water) and natgas to heat the water (contaminated fracking water). I bet using the usual journalist sophistry techniques I could get your home sink up to 10:1 ratio pretty easy. Maybe not the hundreds to one ratio in the article, but close.
  - nixy 11y ago
    The dishwasher etc is not part of producing the drinking water. It's just a way of consuming it. But I get your point about the entire construction of the well. And the drilling rig, say it drills 500 wells in its life span. Then you have to consider the water that went in to building the rig, divided by 500. And the water that goes in to disassembly and recycling. And the water that went in to building the drill rig factory. And that went into building the tools that were used to build the factory. Etc.
    - JoeAltmaier 11y ago
SixSigma 11y ago
Dunedin in Florida filters 13,250,000 litres per day using reverse osmosis and claims 100% of water is recycled for drinking. http://www.switchurbanwater.eu/outputs/pdfs/W1-1_1-2_GEN_PAP_Integrated_Urban_Water_Management_in_Dunedin_USA.pdf http://www.switchurbanwater.eu/outputs/pdfs/W1-1_1-2_GEN_PAP...
- mbarrett 11y ago
  For comparison, a big-box purchased reverse osmosis home setup could have up to a 4:1 waste water ratio.
  - SixSigma 11y ago
    Yeah, I was amazed both when I saw how much water got wasted in home RO and how much wasn't wasted in industrial RO!
    - mbarrett 11y ago
      There are a few more parts you can buy for the home install to make it more efficient. I can see the manufacturers leaving it out due to install space and cost. My system is relatively new, but this thread has my thinking of ways I can better use that 4 gallons of waste.
      - SixSigma 11y ago
        That's handy to know. I was investigating whether I could make my hydroponics system recycle the water but the waste ratio made it unattractive - it was only for science.
ars 11y ago
You have to define "used". To have drinking water, you need HUGE volumes of other water to dilute and clean it. Only a small fraction of it is actually drawn for drinking, but rest still has to be there. So does that rest count or not?
iNate2000 11y ago
The PDF article said that about 20% of the water footprint is from packaging. Bottled water has to be close to that.
Shivetya 11y ago
Not just drinking water, but what of any liquid sold at the store? How much water does that milk take to produce by the gallon, orange juice, and such. I do know that in many plants most of the water is recycled as its cheaper than sending it out of plant. Even car washes recycle water for reuse.

sanxiyn 11y ago

Quick search gives http://www.npr.org/sections/thesalt/2013/10/28/241419373/how-much-water-actually-goes-into-making-a-bottle-of-water http://www.npr.org/sections/thesalt/2013/10/28/241419373/how... which is not very easy to interpret.

nxzero 11y ago
That's bottled water, not tap water. My guess is it varies greatly to due the source of the water. At the extreme, I would guess that desalination of saltwater to make it usable for drinking water would likely consume huge amount of water per drink unit of water. Given that it's a pretty obvious question, find it interesting that it is not addressed; reason likely is most reporters do not do investigative journalism, but many will publish as is a story forwarded to them. Lastly, it's very likely some water used was not drinkable to start, reused, etc. - which is to say, it's a complex topic and without a clear question and an understanding of why it is being ask, you'll always get an answer that appears to answer something.
- arviewer 11y ago
  How would desalination cost water? You vaporize water, catch and cool it back to water, and there you go. The cost here is energy, which varies greatly depending on the sun.
  - nxzero 11y ago
    Unclear how much you know about the topic, but there are a number of ways to desalinate salt water, including just mixing non-toxic saltwater with drinkable freshwater; that said, it requires 31 liters of freshwater to make one liter of saltwater drinkable. Normal saltwater has a salt concentration of 3.5% and to be drinkable that must be reduced to 1000 ppm (parts per million); which is to say, say for 100 liters of saltwater, you'll lose at least 3.5 liters just to reclaim the freshwater itself. Beyond that it'll depend on the system how much additional volume is lost in the desalination process; quick Google finds some systems that lose 20% of the volume per unit processed. Lastly, your reference to energy consumption brings up an example of additional sources of water lose. Water used to cool systems, water used to clean systems, leaks/waste, etc.
    - nxzero 11y ago
      Not that I post for rep, or for that matter care about downvotes, but if you're expressing that the above comment was not of use, on-topic, opinionated, bad tone, etc. - it's not clear why. Please comment so that I might be able to address your concerns. Cheers!
    - arviewer 11y ago
      When you need 31 galles of freshwater to make 1 gallon salt water drinkable, you have 32 gallons of drinkable water. Those 32 gallons are not wasted. When you make one jeans or a t-shirt, you may need many more gallons. You cannot drink that water afterwards, so that totally different.
      - nxzero 11y ago
        Reference to using freshwater for desalination has nothing to due with waste, but to make the point that boiling saltwater is only one of many ways to desalinate saltwater.

2muchcoffeeman 11y ago

You'd have to distinguish between potable water and just any water too. https://en.wikipedia.org/wiki/Drinking_water https://en.wikipedia.org/wiki/Drinking_water mentions that Christchurch, NZ has a sufficient supply of pure enough water that no treatment is required. So you could probably build a passive filtration system for a one time cost. It just may not be fast enough to treat enough water if your population is too big.

ioquatix 11y ago
I live in Christchurch and I can confirm our water is AWESOME.
- acveilleux 11y ago
  So's your coffee!

Retric 11y ago

Very little water is lost in municipal water filtration. The largest loss is generally evaporation from dam reservoir which is on the order of 10%. Depening on location temperature, humidity, ect. Don't forget you drink the same water you bathe with. At scale it's producing a lot of water. PS: Now a lot of water is lost after filtration by leaks/breaks in water pipes. But, that's mostly an economic choice as water is really cheap replacing pipes is expensive.

DougN7 11y ago
To compare to this article you'd also have to calculate the amount of water used to make the pipes, dig the ditches, create the machinery to dig the ditches (and pro-rate the machinery's life time against the amount of time it's used to dig water pipe trenches), fuel used, etc, etc.
- Retric 11y ago
  Your scale is off. The city of Philadelphia for example loses 60 million gallons per year to leaks out of 250 million gallons pumped from the river. (excluding leaks at the home and business level estimated at 1trillion gallons per year in the US.) To get anywhere close to similar levels from the article you replacing there entire system every 20 years would need to take 20 * 60m * 340 = 408 Trillion gallons of water.
logicrook 11y ago
The point he is making is not reduced to that, it is that you should judge things with the same metrics. I.e. how much water is used for bottled water? For running water? How much harmful chemicals can you find in soft drink, bottled water, tap water? (because running water may be very cost-efficient, but it comes with a price, the dizzying quantity of chlorine you can find inside being one). Just giving one number out of your hat is a dishonest persuasive move (unless everybody already knows the numbers for all the previous questions), precisely because the author knows very well that most people cannot put that number into perspective. This is not a very scientific attitude for something published in a 'scientific' journal.

nixy 11y ago

At home I have a 1:1 ratio. I've got my own well and my own pump, so every liter of water I get out of the well flows out through my tap. I guess you could argue that the electricity needed to work the pump may be produced by means that waste water.

VLM 11y ago
The mine that dug the iron that made your pipes contaminated a lot of water. In the vegan world its standard to count every drop of rain that hit the livestock pasture as being used, therefore its fair to count the rain that ran off the factory roof where the pump was manufactured as used. Wells don't dig themselves and although that doesn't happen often, it does take a lot of water to do it, and make the gear to do it, and get the diesel fuel out of the ground and onsite to run the drilling rig. I drink every drop from a can/bottle, usually, but I am a bit wasteful in the kitchen sink and probably only half the tap water is swallowed. Not to mention my dishwasher uses 5 gallons or 10 gallons or whatever small number every time it cycles and washes my drinking cup (so my drinking cup's share is only maybe 1/2 cup of dishwasher cycle water, but, maybe I was only thirsty for 1/2 cup of water leading to 50% efficiency right there). And of course the dishwasher uses electricity (water) and detergent (water) and natgas to heat the water (contaminated fracking water). I bet using the usual journalist sophistry techniques I could get your home sink up to 10:1 ratio pretty easy. Maybe not the hundreds to one ratio in the article, but close.
- nixy 11y ago
  The dishwasher etc is not part of producing the drinking water. It's just a way of consuming it. But I get your point about the entire construction of the well. And the drilling rig, say it drills 500 wells in its life span. Then you have to consider the water that went in to building the rig, divided by 500. And the water that goes in to disassembly and recycling. And the water that went in to building the drill rig factory. And that went into building the tools that were used to build the factory. Etc.
  - JoeAltmaier 11y ago

SixSigma 11y ago

Dunedin in Florida filters 13,250,000 litres per day using reverse osmosis and claims 100% of water is recycled for drinking. http://www.switchurbanwater.eu/outputs/pdfs/W1-1_1-2_GEN_PAP_Integrated_Urban_Water_Management_in_Dunedin_USA.pdf http://www.switchurbanwater.eu/outputs/pdfs/W1-1_1-2_GEN_PAP...

mbarrett 11y ago
For comparison, a big-box purchased reverse osmosis home setup could have up to a 4:1 waste water ratio.
- SixSigma 11y ago
  Yeah, I was amazed both when I saw how much water got wasted in home RO and how much wasn't wasted in industrial RO!
  - mbarrett 11y ago
    There are a few more parts you can buy for the home install to make it more efficient. I can see the manufacturers leaving it out due to install space and cost. My system is relatively new, but this thread has my thinking of ways I can better use that 4 gallons of waste.
    - SixSigma 11y ago
      That's handy to know. I was investigating whether I could make my hydroponics system recycle the water but the waste ratio made it unattractive - it was only for science.

ars 11y ago

You have to define "used". To have drinking water, you need HUGE volumes of other water to dilute and clean it. Only a small fraction of it is actually drawn for drinking, but rest still has to be there. So does that rest count or not?

iNate2000 11y ago

The PDF article said that about 20% of the water footprint is from packaging. Bottled water has to be close to that.

Shivetya 11y ago

Not just drinking water, but what of any liquid sold at the store? How much water does that milk take to produce by the gallon, orange juice, and such. I do know that in many plants most of the water is recycled as its cheaper than sending it out of plant. Even car washes recycle water for reuse.