I think they are intertwined.
If politicians could provide fresh water for free they’d do it. They do not because it is not free and desal costs a lot so no one wants to pay for it.
It’s not a technical problem inasmuch as we know how to desalinate water. If there is a technical problem it is how to do that cheaply (as these things go) and transport the water to places like Arizona. That will not be cheap considering the scale these things would need to operate at.
Again, you don’t need to transfer water to Arizona, just water rights. That makes it a political problem, not a technical one.
Desal water is expensive but not intolerably so. Residential water rates here are $7.64/HCF, or $3228/acre-foot. The Carlsbad plant is $2725/acre-foot. Distribution costs something, but it’s clearly in the ballpark of reasonable residential rates. Untreated Colorado river water costs $1579/acre-foot in comparison. So less than double.
I had an AI do some research, and while I won’t post the results here, it did come up with some interesting (cited) things. First is that I’m not the first to come up with the idea. Second is that the political problem is vastly more difficult between upper- and -lower-basin states. An agreement between Arizona and California (both lower basin) might be possible. But probably not between Colorado and California.
I think the issue is the cost of water for farmers and other industries (like the new TSMC fab in Arizona which needs huge amounts of water) which use a LOT more water than residential and they will always save that penny per gallon which is not a big deal to you and me but adds up to a lot for them.
And they have more power over politicians than you or I do.
Farmers are an issue in that they tend to have ancient water rights and a great deal of political power. Municipalities use almost nothing in comparison.
The TSMC fab uses almost no water compared to its economic output. It’ll probably contribute ~2% to Arizona’s GDP but water use will be <0.1% of the total, and <0.02% once they start recycling.
There is a basic physical principal to consider: Water flows toward money.
Water use is not about economic output. If the TSMC fab uses 0.1% of the water that is equivalent to 480,000 48,000 people in the Phoenix metro area.
Maybe they will get better…maybe not. But at the start, one factory will consume the water needed for 480,000 48,000 people (assuming the number you cited is correct).
ETA: Bad math. Sorry.
I wish that were more true, but in fact water is used on a ton of very low-value industries, while high-value industries have to beg for it. The TSMC fab in Arizona being a good example. Even without recycling, it produces vastly more economic value per gallon than farming. And yet the water use was an enormous political obstacle. It’ll produce ~$10B/yr in revenue but use less water than a farm that makes $30M/yr in product.
I wonder what the respective local payroll for the farm versus the fab is. Revenue is nice, but that’ll all be exported to corporate headquarters or overseas. Eventually some of it turns into widely dispersed dividends, but not much.
Sure it is.
More like 40,000. Initial TSMC water use is 4.75M gal/day, while Phoenix use per person is 120 gal/day.
Once the recycling systems are running it’ll go down to 1M gal/day, or the equivalent of 8300 people.
But that’s still besides the point. Cities are still relatively high-value water users. Farming on the other hand uses 74% of Arizona’s water but only produces $23B/yr in output, while TSMC will use less than a tenth of a percent and will produce ~$10B in output. And that’s average. Half(ish) of those farms are even worse than the average!
But none of that matters because farmers are so protective of their water rights and it’s very difficult to transfer that water to more productive uses.
I just noticed that.
My mistake.
I’ll believe that when I see it. These kinds of promises have a way of not happening and once the fab is built it is really too late to do much about it.
I hope they manage to do it though. I really do.
I stated the non-recycling numbers first for that reason. It doesn’t change the overall economic picture. It might be a nice-to-have eventually, but either way the water use is completely dwarfed by much lower-value industries.
Good points!
I didn’t know that, and it’s very interesting. I found what’s below, and it is pretty darn daunting in terms of being a possibly insoluble problem.
Here’s a breakdown of the problem and its associated issues:
- Brine as a Waste Product:
Desalination plants, which aim to remove salt from seawater to create freshwater, inevitably produce a large amount of highly concentrated brine, which is a major waste stream.
- High Salinity and Chemical Content:
This brine is significantly saltier than the original seawater and often contains residual chemicals used in the desalination process, like anti-scalants and anti-fouling agents, further impacting the environment.
Environmental Impacts:
Disrupted Marine Ecosystems: The discharge of concentrated brine can lead to:
- Increased Salinity: This can be toxic to many marine organisms and alter the delicate balance of coastal ecosystems.
Reduced Oxygen Levels: Brine can deplete dissolved oxygen in the receiving waters, potentially leading to “dead zones” where marine life struggles to survive.
Chemical Contamination: Chemicals in the brine can pollute the marine environment, posing risks to both marine life and potentially human health.
Impact on Shorelines and Sediments: The high density of brine can cause it to settle on the seafloor, potentially smothering or disrupting bottom-dwelling species.
Ship it to the sun!
I kid, I kid! 
And 4th stage purification has hardly any of those issues, and it is cheaper. Not to mention- you dont need an ocean.
The desal plant in El Paso, TX, not having a convenient coastline, uses deep well injection for its effluent disposal. I haven’t seen a cost breakdown.
Thus far, it appears they have not lubricated any fault lines.
Maybe they’re doing just enough injection to offset the consequences of fracking for oil?
Two offsetting pollutants is an RW industrialist’s dream.
Both are issues.
Fracking uses vast amounts of potable water. Using any old water, much less salt, fouls the equipment. So, it exacerbates existing water issues. It doesn’t offset anything.
Deep well injection can work, but the thing about wells is we’ve deliberately created subsurface zones where fluids shift about in new ways under the ground plus they’re leaky (that’s how we get at the stuff we want).
When you combine them, even aside from adding desalination brine? There’s potential to contaminate groundwater over vast swaths of land, rendering some of it uninhabitable. That can very well defeat the purpose. Of course, injection wells are planned as best as possible, but we don’t possess knowledge of the subsurface to anything near the level of detail required to prevent all such leaks.
Where do they get the salt water to treat in the first place?