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Control and Prevention (CDC) in Atlanta, Georgia. “Go to Philadelphia, go to Baltimore – the water treatment facilities look like Greek temples, because it was probably one of the greatest public health achievements we had put in place.”

But since then water infrastructure has tended to lie out of sight and out of mind – and it is crumbling. Last year alone, Thames Water, which provides water for London and parts of south-east England, lost 646 million litres every day to leaks from its 31,000 kilometres of pipes, enough to meet the needs of 3 million people. The company puts the cost of replacing its entire network at upwards of £12 billion.

In the US an estimated 240,000 mains water leaks occur each year. In a particularly

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IN A garden shed called Stanley on the bank of a muddy pond, Darren Reynolds is about to have a drink. The pond’s less-than-limpid

waters would normally flow through the surrounding reed beds to a drainage channel. Reynolds, however, is pouring himself a perfectly clear glassful.

What’s in his shed gives him reasonable confidence in what he is doing: it contains a mini treatment plant that can produce drinkable water on demand. Conceived for places with no fixed water infrastructure, such as refugee camps, Reynolds thinks that with a little tweaking it could be just the thing for more suburban locales, too.

A professor of health and the environment at the University of the West of England in Bristol, Reynolds is one of a band of researchers advocating a fundamental shift from the way we pipe water now. Just as the future of electricity is seen by some to lie with a decentralised network of small-scale producers, the way to lessen water woes in countries across the globe could be for each of us to take charge of our water treatment ourselves. It is a bold vision – but can it work?

Clean water is the most basic of necessities: in 2010 the United Nations declared it a fundamental human right. Yet the World Health Organization estimates that over 1 billion people are without clean drinking water, while more than one-third of the world’s 7 billion people lack basic sanitation.

In nations such as the UK and the US, meanwhile, access to safe drinking water may generally be easy as turning on a tap, but what lies behind that is often forgotten. “At the turn of the last century, putting water treatment in was how a city proved it had made itself,” says Michael Beach of the US Centers for Disease

spectacular incident last month, a ruptured pipe in Los Angeles sent some 90 million litres of water gushing down Sunset Boulevard and through a campus of the University of California. In a report to Congress last year, the US Environmental Protection Agency estimated that $384 billion of infrastructure investment would be needed to deliver drinking water across the US for the next two decades. Some say the figures should be even higher, factoring in the costs of protecting supplies from the more frequent extreme weather events predicted for the future, courtesy of climate change.

Water market researcher Brent Giles of international firm Lux Research is sceptical of these gloomiest predictions. “People who say it will take trillions of dollars of infrastructure investment are typically civil engineers,” he says – and they love their grand designs. Nevertheless, Giles concedes the problem is undoubtedly huge.

Leaky pipes are expensive to fix, but also a health hazard. “Once the water pressure is below a certain point, that’s when things can move in,” says Beach. It’s a problem often compounded by the tendency of laying clean-water and wastewater pipes close to one another. A Norwegian study in 2007 implicated leaky water pipes in many cases of gastrointestinal illness there. In 2009/10, the most recent years for which figures are available, the CDC tracked more than 30 US disease outbreaks back to contaminated public water supplies. “It’s a crumbling infrastructure problem, not a country problem,” says Beach.

The fixes we have at the moment are not ideal. To combat hazardous microbes, utility companies in the US and UK add tiny amounts of chlorine to their treated water. >B

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litres of water lost through leaks in the uk every Day

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Chlorine treatment in general has raised concerns, as chemical by-products of the process have been tied to health problems including bladder cancer and genetic defects.

To stem leaks more quickly, companies such as IBM are developing smarter water management systems that can monitor the rate of flow and respond quickly to pressure drops. Quest Inspar, a company based in Houston, Texas, has developed robots that travel through pipes to find leaks and coat any cracks with sealant.

For Reynolds, such solutions are papering over the cracks. What is needed, he says, is a rethink of the underlying paradigm. “We dirty water, treat water, and then pump water, and then we do it again – at great cost,” he says. Most of our water infrastructure is in place to deal with the 150 or so litres of wastewater each person produces every day. According to figures from industry body Water UK, this water is sullied by just 60 grams of organic matter – less than 0.1 per cent of the total flushed.

If we could treat this waste closer to home, recycling dirty water and bringing it up to drinking standard, that could reduce costs and minimise the health risks of leakages in the wider pipe network. Such an approach

might also provide a cheaper way to ensure clean water and sanitation for poorer countries with little established infrastructure.

Local water purification systems have existed for years in places off the water grid – from remote homesteads to the International Space Station. They come in a range of shapes and sizes, including sand filters for rain barrels that physically trap microbes and other contaminants, solar-powered rooftop purifiers that use light to break them down,

and pots lined with nanoscale particles of silver that kill microbes on contact.

But such systems tend to be very small-scale, providing no more than the minimum water requirement for a family. In his shed, Reynolds is working on something a little bigger. He takes water from a pond on the university campus and passes it through a series of filters and membranes to remove impurities. Along the way, a small amount of brine solution is added that has been zapped with a current, releasing hydroxyl radicals, hypochlorous acid, chlorine ions and other related substances that act as disinfectants.

This current can be created using energy collected by a solar cell. When the current is switched off again, the disinfectant reverts to brine, sidestepping the environmentally troublesome residues that can be left behind by direct chlorination. Reynolds’s tests have shown that the concentration of common pathogens dropped below detection limits with just 10 to 20 seconds of treatment. And what works for pond water should also work for wastewater from the home. “It could almost certainly be used for treating ‘grey water’, the stuff we are flushing down the toilet or sink,” he says.

He’s not the only one moving in this direction. Water researcher Jörg Drewes at the Technical University of Munich, Germany, and his team have developed a system that attaches to a building’s pipes before water flows to the taps. It combines filtration membranes with treatments using oxidation and ultraviolet light to break down contaminants, and produces drinking-standard water from a variety of wastewater supplies.

Commercial products are becoming available too. Puralytics, a firm based in Beaverton, Oregon, markets “Solar Bags” that use sunlight to render contaminants harmless, but has also developed larger systems that deal with higher volumes of water and use LEDs for places where sunlight is not available. Others, such as General Electric and the Australian company Aquacell, are developing systems based on filtration membranes covered in a film of helpful microbes – a common technology in large-scale wastewater plants – to “mine” wastewater of harmful substances and treat it for reuse.

Ben Grumbles of the pressure group US Water Alliance believes we now have the technology to make decentralised water treatment work. “There are competing visions, to centralise or not to centralise,” he says.

“There are 2.6 billion people in this world who don’t have access to sanitation,” says Orianna Bretschger. More people have access to a mobile phone than a toilet.”The researcher at the J. Craig Venter Institute in La Jolla, California, is developing a small solution to that large problem. Her microbe-based water-treatment systems pull pathogens from water – while producing fertiliser as a by-product, and generating power to boot.

Large wastewater utilities in wealthy nations already use “activated sludge” containing microbes to break down organic matter. But where oxygen is readily available, nasties such as E. coli can also thrive. The treatment must be combined with extra processes, such as expensive reverse osmosis or large-scale chlorination, which are impractical in the developing world.

Bretschger and her colleagues have instead concocted a cocktail of sewage-treating bugs that thrive without oxygen. This mix of microbes could break down water-borne organic matter while outcompeting the nasty bugs that need oxygen. They would borrow electrons

from surrounding metal surfaces to “breathe”, creating a current that could also be used to power bathroom facilities. That would make for a lasting and low-maintenance solution in developing countries with little water infrastructure, Bretschger says.

Last year the philanthropic Roddenberry Foundation gifted her $5 million to continue developing the system and bring its output up to drinking standard. Bretschger’s prototype is only about the size of coffee cup. “We need to demonstrate consistency and reliability in a tank the size of a building,” she says.

This month, her team will be assembling the components to build a full-scale version with students in a nearby high school. That will serve a dual purpose, she hopes: to prove the system works, and to start to change mindsets. “Public perception has a lot to do with the success of these ‘toilet-to-tap’ projects,” she says. “I like to say ‘showers to flowers’: all of our water is recycled, it’s just a matter of how we do it and the time it takes to get that water back to you.”

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“Should we have a continued reliance on modern centralised wastewater and drinking utilities, or do we increasingly move to the ‘spaceship’ model, where homes and businesses are off the grid in certain respects?”

The most obvious benefit would be to people in those developing countries in which there isn’t much water infrastructure (see “Sludge power”, opposite page). But as far as wealthy countries are concerned, Giles for one is less convinced that off-grid water will wash.

Reverse plumbingHe thinks it makes sense to encourage local water recycling, using lightly, locally treated recycled water for watering lawns, washing cars and the like. But he worries that if homeowners or building managers, rather than local authorities, must produce their own drinking water, vulnerable populations such as the elderly and the poor may end up with unclean water.

Beach agrees that any transition to off-grid water would need stringent regulatory and legal frameworks. The lesson of what happens when homeowners are responsible for their own filtration and pipe systems comes from the 16 million households in the US that get their water from private wells, he says. The rules say they have to prove their wells are clean, but in practice there is little oversight. “What that means is nothing gets done.”

Drewes suggests that a switch to local water treatment would require companies and experts – call them reverse plumbers – who either come in to check decentralised water purification systems or use smart meters to monitor them from afar. He and

his team have recently started investigating the scales at which each of these models would be economical with the local purification systems they have developed.

Other problems would need to be solved, too – not least a powerful yuck factor when it comes to perceptions of “toilet-to-tap” water treatment. For that reason and others, Drewes believes the most likely move in the developed world is not a wholesale switch to off-grid water, but some form of hybrid solution. He envisages old, patched-up pipes continuing to distribute water in the volumes we demand, but treated to a lower standard. At local treatment facilities, it would undergo further treatment to bring it up to par. Grumbles also sees the future in a hybrid model of “centralised systems delivering water, but not fit to drink”.

Reynolds is still working on his own solution. Since January, he has been operating a larger purification system in his shed that can pump out 3000 litres an hour, enough for 1500 people’s most basic needs. Working together with Portsmouth Aviation, he has developed a lorry-sized version capable of treating 18 to 20 cubic metres an hour. It is being trialled in Romania, providing water for communities that normally depend on boreholes polluted by contaminants including agricultural run-off. The by-products extracted by treatment are so rich in nitrogen that they can themselves be used as fertiliser.

It’s early days for off-grid water, Reynolds admits, but the costs of maintaining and extending existing water infrastructure will sooner or later force a rethink, he says. “In the world of the future, it is not going to pull us all through.” n

Naomi Lubick is a freelance writer based in Stockholm, Sweden

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