Recycling wastewater for drinking


The state of California in which I live has had many years of drought leading to water shortages. While conserving water is one way of addressing the problem, another is to increase the supply. One option is to use desalination plants but those are expensive to build and operate. Another is to reclaim wastewater for use in things like irrigation. But recently the state has gone one step further and approved reclaiming wastewater for human consumption.

When a toilet is flushed in California, the water can end up in a lot of places: an ice-skating rink in Ontario, ski slopes around Lake Tahoe, farmland in the central valley.

And – coming soon – kitchen faucets.

California regulators on Tuesday approved rules to let water agencies recycle wastewater and put it into the pipes that carry drinking water to homes, schools and businesses.


Orange county in southern California operates a large water-purification system that recycles wastewater and uses it to refill underground aquifers. The water mingles with the groundwater for months before being pumped up and used for drinking water again.

California’s new rules would let water agencies take wastewater, treat it, and put it into the drinking water system (although not require them to). California would be just the second state to allow this, following Colorado.

The vote was heralded by some of the state’s biggest water agencies, which all have plans to build huge water-recycling plants in the coming years. The metropolitan water district of southern California, which serves 19 million people, aims to produce up to 150m gallons (nearly 570m litres) per day of both direct and indirect recycled water. A project in San Diego is aiming to account for nearly half the city’s water by 2035.

Water agencies will need public support to complete these projects – which means convincing customers that not only is recycled water safe to drink, but it’s not icky.

California’s new rules require the wastewater be treated for all pathogens and viruses, even if the pathogens and viruses aren’t in the wastewater. That’s different from regular water-treatment rules, which require treatment only for known pathogens, said Darrin Polhemus, the deputy director of the division of drinking water for the California water resources control board.

In fact, the treatment is so stringent it removes all the minerals that make fresh drinking water taste good – meaning they have to be added back at the end of the process.

This should not be a problem. It is not as if the potable water we get from rivers, lakes, springs, aquifers, and reservoirs is somehow pure. Those sources may have animals, dead and alive, in them and ground water can contain all manner of pollutants due to run-offs from farms and factories. That water has to be treated before it enters the public water supply. So we are already used to drinking water that started out dirty. But people tend not to think about that.

There will undoubtedly be people who will recoil because of the ‘ick’ factor at the thought of drinking water that was once used to flush toilets. But when you think about it, water has no memory, other than in the imaginations of those who believe in homeopathy. Once you have removed any harmful contaminants, it is just water. In the effort to make people accept this, the measures taken to treat the wastewater will make this water actually ‘cleaner’ than the water we have now. Already astronauts in the space station recycle 98% of the water they use, such as their urine and sweat. Their recycled water is cleaner than what we drink on Earth.

The bottled water industry has done an excellent propaganda job in persuading people that the water they sell is better or purer than tap water. But in most parts of the US, tap water is perfectly fine and I drink it all the time. I never buy bottled water, preferring to fill up a bottle with water if I think I may need water in a location where it is not easily available. I also don’t drink much water, just about 24 oz a day. But I know people who think that they need to drink a lot of water all the time (another success for the bottled water industry propaganda) and only drink bottled water and also only cook with it. As a result they are constantly carrying heavy cases of bottled water to their home and then having to recycle the plastic empties, leading to problems with plastic pollution.

Comments

  1. says

    Humans will try anything except not exceeding the carrying capacity of the environment. The one obvious solution to all of our problems that scale per capita is to stop breeding and let the population stabilize around 250mn. Of course, we’d rather see our children die than stop making them.

  2. raven says

    This isn’t all that much different from what we do now.

    Most cities on rivers discharge their treated sewage into those rivers.
    Which is also where they get their drinking water from. For example.

    Minneapolis, Minnesota:

    About 12 hours after it arrived, the water is now ready to flow into the Mississippi River. During the summer months, when people may be swimming, it is further disinfected with bleach and a bleach neutralizing chemical.

    It is cleaner than the river it is entering, but the council says it is not safe enough to drink. Minneapolis and St. Paul residents drink water pulled from the Mississippi River, but only after purification at special drinking water treatment plants.

    Minneapolis gets its drinking water out of the Mississippi river.
    Its treated sewage goes right back into that river.

    All the many cities on the Mississippi river do the same thing.
    “More than 50 cities rely on the Mississippi River for daily water supply (Environmental Protection Agency)”

    Even New Orleans at the very end of the Mississippi gets its domestic water out of the river.

  3. Katydid says

    @Raven, everyone I know in New Orleans gets bottled water delivered to the house. Now I know why.

  4. nomenexrecto says

    I live in a city on a big river, and close to the limits of the town just upriver. Their water recycling plant is right next to our city limits… as are ours to the next town downriver. And so it goes…
    Actually, my city and the neighbouring towns all get tap water from a reservoir some 30 mile upstream on a tributary, where there are no towns even further upstream.
    The next big city downriver uses refined river water, however, and a good million people have been surviving this for a century…
    Unless you think about it and “ick”, it’s actually a non-story, I guess…

  5. Heidi Nemeth says

    Dirty water which is kept underground for a year or two or three does not become clean water, though most people, including politicians, think it does.

    Most older American cities have sewer systems which do not totally separate storm water from sewage water. Heavy rains cause CSO’s -- combined sewer overflows, where storm and sewage water mix. Sewage treatment plants can’t deal with the overly large volume of water, so they discharge much of it, untreated, into the rivers, streams and oceans. Here in New York City, rainfall over 0.05 inch in twenty four hours triggers CSO’s.

    And, it turns ot, septic systems don’t work to purify sewage water, either. This was discovered a couple of years ago.

    Sewage treatment plants can be very good at making water more than clean enough to drink. But I still thought the tap water in New Orleans tasted bad.

  6. robert79 says

    “The bottled water industry has done an excellent propaganda job in persuading people that the water they sell is better or purer than tap water. But in most parts of the US, tap water is perfectly fine and I drink it all the time.”

    My tap water actually comes from the same source as a popular brand of bottled water. Except the health regulations on tap water are a lot stronger than on bottled water, so my tap water is actually “purer” than the bottled variant.

  7. Rsimons says

    Windhoek has recycled its water for 25 years or more, but they usually do not publicize it. Normally about 8% is recycled but it can get to over 20% if required.

  8. Robbo says

    There is a calculation you can find on the internet. Caesar’s Last Breath. the calculation shows that any particular breath you take probably has air that Julius Caesar exhaled as he died. I redid the calculation years ago, but to find what are the odds that the sip you just took of your coffee has a water molecule that was in Caesar’s last urination.

    iirc, odds are good. 50-50 or so.

    Even more thought provoking, since estimates are there have been 10^13 or so modern humans of our species, and 10^13 is much smaller than one mol, odds are pretty good that cup of coffee contains water that a significant fraction of those 10^13 humans urinated.

    and *every* dinosaur too.

    You have been drinking water already used by billions and billions of other creatures.

  9. Holms says

    #11 shanti
    I’m going to venture a wild opinion: clean water at the tap is better than unclean.

  10. John Morales says

    Holms, I believe shanti is expressing that tap water is cheaper and more accessible than bottled water; that is, that tap water is good enough water — with a bit of boiling, in this case, just to be sure.

    In short, shanti and I share the same opinion.
    Paying for water rather than using tap water, when available, is for saps or for people who have money to waste.

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