Doubts about Water Consumption: Unanswered Questions

[pattylou]

I admit, I don't understand the basic argumnet that we will "run out of water." I understood that fresh water falls as rain at a fairly steady pace. If I use water from the hose to water my plants, instead of "grey water," for example, there is still as much water in the global system and it will easily and quickly reenter the cycle.

Is the concern that more and more water treatment plants will be needed? That this will have a cost attached to it?

Why is there a concern that we will "run out" of water?

(I have a headache this morning from too much socializing last night and I appologize if this post is not clear.)

 

[Phobos]

Good topic.

As you suggest, the world as a whole has plenty of water. The problem is having enough clean water in the right places ("clean" meaning potable). Most water is non-potable without tons of treatment (e.g., salt water) or inaccessible without extreme recovery measures (e.g., ice caps, glaciers, water vapor, deep groundwater). Some small percentage is readily available for human consumption. Something like this...

oceans/seas - 94% (too saline)
groundwater - 4%
ice caps/glaciers - 2%
everything else - < 0.1% (this includes all freshwater lakes, rivers, etc.)
source: "Groundwater", Freeze & Cherry, 1979

So the sources we use are fresh surface water sources (lakes, rivers) and groundwater.

Most sources are not potable without some level of treatment (particularly for urban centers and particularly as we continue to pollute our water supply).

So we run up against 2 big factors:
(1) Treatment plants have limited capacity (limited amount they can treat in a day). You can build bigger plants, but that's very expensive.
(2) A particular region has a limited amount of storage capacity. For example, when you draw groundwater it is replaced by the hydrologic cycle, but only at a certain rate. So if you extract groundwater faster than it is replenished, then your wells will run dry.

Water rights are a big issue. If your city runs out of water capacity, technologically, it could simply bring in water from another area to augment its supply. However, politically, people from that other area are unlikely to give up their water supply to you.

 

[pattylou]

Desalination seems like it should be easy. It could even be lowtech (boil water and capture the steam, re-condense it.)

When hiking, chlorine tablets or small filters allow potable water.

It sounds like the alarms that are raised for water --- have more to do with large scale urban areas, not individuals who just need something to drink? In other words, we won't die of thirst, but may ultimately see pressure for --- fewer fountains outside Vegas casinos, fewer grassy lawns in dry areas, and so on?

(I understand that depleting groundwater, aquifers, etc, will have effects on species that rely on this water, and that is awful. But it's also sort of a separate question; in this post I am curious about the alarms that are occaionally rung for humans wrt water.)

 

[CobblyWorlds]

In Europe, the mediterranean, are drought has been caused by a shift in the Arctic Oscillation, http://nsidc.org/arcticmet/patterns/arctic_oscillation.html. This exacerbates the issue of water tables falling due to over-extraction because they're simply not filling. The dry conditions cause obvious problems with reservoirs.

The area where I live, the fylde, behind Blackpool northwest UK, had boreholes for water extraction, but gradually they've been phased out, starting with the ones near the coast. This was because the extraction of fresh water from the aquifer has drawn salt water in from the sea, making the wells useless (unless you want to fill a very large salt-water fish tank).

The reasons for individual water shortage issues are many and often quite specific to the area considered.

 

[Andre]

It could even be lowtech (boil water and capture the steam, re-condense it.)

I'm afraid that the energy required for that is prohibitive costly. But if you have unlimited solar energy available you could use http://www.txses.org/epsea/stills.html on a massive scale.

 

[Marijn Blom]

There are several problems around (drinking water) in europe and the US.
One of the problems is the location of useable freshwater.
In the US for instance LA (or that what my memory tells me, could be San Fransisco, if i´m not mistaken there is a tread about it on the forum already) has a vast need for freaswater. But it hasn´t the capacity to sustain the consumption itself. It drawas water from several rivers, causing those to loose quite a lot of their flow volume resulting in silting e.g.

Another problem is cleaning it. A problem in europe results from anticonception means, namely the pill. The hormones in the pill are , excuse the expression, pee´ed out again, and entering the blackwater circuit. problem is, they aren´t filtered out before the water flows back to the surface water system. The same system that delivers the water used to make drinking water out. This causes the costs to purify the drinking water to sky rocket, or the hormones are left in. This in turn isn´t good as well.

P.s. this was a hasty post, i´ll reread and edit when i´ll get back.

 

[Andre]

Here is a better link. http://www.solaqua.com/solstilbas.html

Now 2 (winter) -6 (summer) liters per m2 per day or (I think) 6-18 fl oz per ft^2. Now image how many square miles of solar stills you could build at the sea sides near deserts for the lost money of Kyoto. But you have to make choices of course.

 

[Phobos]

Desalination seems like it should be easy. It could even be lowtech (boil water and capture the steam, re-condense it.)

When hiking, chlorine tablets or small filters allow potable water.

Easy, but cost-prohibitive in most cases (particulary for urban-scale). Although there are a few examples of large desalinization plants in areas where is is cheaper than piping in water from faraway.

It sounds like the alarms that are raised for water --- have more to do with large scale urban areas, not individuals who just need something to drink? In other words, we won't die of thirst, but may ultimately see pressure for --- fewer fountains outside Vegas casinos, fewer grassy lawns in dry areas, and so on?

That's the basic idea.

Here in New England, summer time "water bans" are common (i.e., restricted use for watering lawns, etc.). Water rights/access is always a big issue for land developers. The State will fight to protect every square foot of wetland space (whereas other states may not be alarmed until many acres of wetlands are involved).

Speaking of http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2005/07/17/CMGHBD9BO41.DTL" , consider the Colorado River. It now runs dry before reaching the Gulf of California like it used to due to all the withdrawals, dams, etc. in the U.S. The people at the end of the river are not exactly happy about that.

 

[hitssquad]

consider the Colorado River. It now runs dry before reaching the Gulf of California

The Colorado River still flows into the Gulf of California.
http://earthobservatory.nasa.gov/Newsroom/NewImages/images_topic.php3?topic=land&img_id=16590

 

[hypatia]

The Colorado River still flows into the Gulf of California.

The problem being that by the time the water reaches the area, its pollution and salt levels make it unusable. The river is so shallow you can wade across it and not get your knees wet. It could be redefined as a slimy brine creek.
The Cucapa Indians, who are last in line for the river, use to be able to support themselves. They depended on the delta floods, which no longer occur.

 

[Pengwuino]

I admit, I don't understand the basic argumnet that we will "run out of water." I understood that fresh water falls as rain at a fairly steady pace. If I use water from the hose to water my plants, instead of "grey water," for example, there is still as much water in the global system and it will easily and quickly reenter the cycle.

Quit stealing our water

 

[russ_watters]

Easy, but cost-prohibitive in most cases (particulary for urban-scale). Although there are a few examples of large desalinization plants in areas where is is cheaper than piping in water from faraway.

As an American, anyway, this is the reason I'm not too concerned about water. At the moment, water is spectacularly inexpensive. And though I don't know the economics of a desalinization plant, for most people, their monthly water bill could double or triple (or more) and it would still be cheaper than their electric bill. For this reason, I'm far more concerned with the economics (and ecologics) of energy.

 

[hitssquad]

To add to your comments Russ, nuclear-power-writer Bernard Cohen has similarly said that water is more of an energy issue than a conservation issue.

See Cohen's book, The Nuclear Energy Option:
phyast.pitt.edu/~blc/book/BOOK.html

 

[loseyourname]

Quit stealing our water

There's the crux of the problem where you live, patty. Southern California, and especially the entire LA area, has no natural water resources of its own (the Los Angeles and San Gabriel 'rivers' are dry 99% of the year). The water is all pumped from other parts of the state, and what used to be fertile farmland is becoming desert.

The Colorado is being killed by the strain of southwestern expansion. Las Vegas and Phoenix, which both draw most of their water from that river, were the two fastest growing big cities in the US during the 90s. I can only imagine that they will lay claim to the that title once come the 2010 census. Outside of LA, people continue to build and move out into the IE and Orange County, further draining what little water resources we still have, and decimating the Salton Sea, which now serves as the last California haven for hundreds of species of migratory birds.

Just another reason I moved away.

 

[Astronuc]

The Colorado River still flows into the Gulf of California.
http://earthobservatory.nasa.gov/Newsroom/NewImages/images_topic.php3?topic=land&img_id=16590

At least when that picture was taken. I have seen images of that same area - dry as a desert. It depends on the time of year and if gates of the dams, like the one at Lake Powell, are opened up to 'flood' the Colorado River. That is a relatively recent policy.

I often fly out to San Diego and I see grevious misuse of water resources. Huge tracks of land out in the desert using water diverted from 100s of miles away - and open aquaducts crossing miles of desert. Some wetlands are now contaminated with salts and minerals including selenium.

 

[russ_watters]

Huge tracks of land out in the desert using water diverted from 100s of miles away - and open aquaducts crossing miles of desert.

I said I wasn't too concerned about this issue, but that's just plain idiotic...

edit: ...But that's what happens when something is (seemingly) so cheap and plentiful. People care little about wasting it.

 

[Phobos]

A quick Googling on the cost of desalinization...

from http://ga.water.usgs.gov/edu/drinkseawater.html
Right now, the high cost of desalinization has kept it from being used more often, as it can cost over $1,000 per acre-foot to desalinate seawater as compared to about $200 per acre-foot for water from normal supply sources

IIRC, desalinization plants also require more land space to construct than standard water treatment plants (a tough order in some parts of the US).