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Dirty Water via Shutterstock

Sunlight can make this dirty water clean...and save lives

Today is World Water Day…but clean tap water is a pipe dream for 780 million people across the globe.

DIRTY DRINKING WATER is a known death trap…but Irish scientists may have a solution.

Researchers from the RSCI can prove that simply exposing dirty water in a plastic bottle to sunlight can kill all but the most resistant bugs.

Professor Kevin McGuigan and his team have already shown that solar disinfection of water (SODIS for short) almost halves the rate of diarrhoea in Kenya, Cambodia and Uganda. Now the team are working on ways to scale up SODIS, upping the effort in the battle against waterborne disease, which kills about one child every 21 seconds.

Harnessing the Sun

Clean tap water is a pipe dream for 780 million people worldwide but SODIS is designed to be used in the home and only needs sunlight, patience and cheap reusable plastic bottles to work.

“You put whatever drinking water you have available in the bottle, place it in direct sunlight and then after a minimum of six hours the water should be safe to drink,” explains McGuigan.

Direct sunlight kills microbes in the water by a combination of heat and UV sterilisation, a process that is effective even when the sun is not ‘splitting the sky’.

“If it is cloudy, we recommend that you put the water out for two consecutive days,” says McGuigan, who has even shown that SODIS can work in Ireland.

During sunny days in June we have put bottles out on the windowsill here and we got complete inactivation of Eschericia coli after two hours, so if you get the sun you get a good effect.

When SODIS was trialled in villages in Cambodia and Kenya, the rate of diarrhoea fell by 40 to 50 per cent.

“We haven’t yet found an important waterborne pathogen that isn’t susceptible to SODIS,” says McGuigan. “Protozoans such as cryptosporidium are more resistant but it can still be accomplished; it just takes a good wallop of energy.”

Limitations

The major benefit of SODIS is the low price tag but this brings its own unique problem.

“The simplicity is its biggest advantage and its biggest disadvantage,” explains McGuigan.

If people see plastic bottles lying in the ditches and you give them a plastic bottle as the solution to unsafe drinking water, there’s not a lot of psychological value placed with the technology.

Even though SODIS has been given the thumbs up by the World Health Organisation (WHO) for use in emergency settings, McGuigan maintains that “the biggest barrier is that people just don’t know about it”.

Another challenge is dissolved solids in the water. Current advice is that if a newspaper headline is still readable through a bottle of cloudy water standing on top, then SODI will still be effective – otherwise it needs to be filtered. In trials, SODIS had a surprise advantage over chlorination, a more widely used method of decontamination.

“The Cambodians thought SODIS was fantastic,” continues McGuigan.

They loved the simplicity and the taste of the water. They don’t like the taste of chlorine, neither do the Maasi people in Kenya.

Building on Success

McGuigan and his team are now working on ways to scale up and enhance the technique.

“There‘s a lot of work associated with SODIS because the most you can disinfect in one go is a two-litre bottle. If you have a family of five or six kids, it’s quite a burden of work.”

Working in collaboration with the Plataforma Solar de Almería in Spain, McGuigan and his team developed a half-pipe reflective cradle that concentrates and focuses sunlight to a 14-litre water bottle.

The system is being tested in Uganda by Rosemary Nalwanga, a PhD student in the Makerere Kampala University, who is co‑supervised by McGuigan and Dr Brid Quilty in DCU as part of the “Water is Life” project, funded by Irish Aid. While the price tag of the system (it cost $200 to make the prototype) puts it out of range of most households, it would be cost-effective in schools or on a community basis.

McGuigan has a curious end-goal for SODIS – he hopes that it become obsolete.

“The ultimate goal is a safe effective water source. It would be better off investing in pumps and better pump technology.”

However, there is caution. “It costs $3,000 to sink a borehole. SODIS is an effective treatment for almost no cost.”

Read: Ireland is to send €3 million more aid to the Philippines

Read: Here’s what Twitter thinks Ireland actually smells like

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41 Comments
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    Mute Ray James Franco Browne
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    Jul 31st 2017, 12:54 PM

    In my bedroom/living room in front of my tv because I live in a bedsit. If I had a separate dining room I would eat there, just to have something different.

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    Mute Tweety McTweeter
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    Jul 31st 2017, 1:31 PM

    @Ray James Franco Browne:

    That’s a bit like me. I usually have my breakfast in the breakfast room, my lunch in the sunroom and my dinner in the dining room. Our breakfast room is currently under refurbishment so I now have to eat my breakfast in the dining room! It’s like a madhouse at the moment! I’ve put Geoffrey on notice and told him that I don’t know how much longer I can put up with it

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    Mute O Swetenham
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    Jul 31st 2017, 12:59 PM

    Usually have my dinner in the alley behind McDonald’s. You’d be surprised with how many perfectly good chicken mcnuggets they leave in the dumpsters back there.

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    Mute Matt Connolly
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    Jul 31st 2017, 1:25 PM

    but how many “kitchen-eaters” have a telly in their kitchen or use their phone/tablet/laptop??

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    Mute Suzie Sunshine
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    Jul 31st 2017, 2:59 PM

    @Matt Connolly: ah but that’s not the question being asked .. that makes for a whole different poll .

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    Mute Ollie Watson
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    Aug 1st 2017, 7:41 PM

    @Matt Connolly: I don’t it’s a good time to talk with your family

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    Mute ktsiwot
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    Jul 31st 2017, 12:47 PM

    In the kitchen, in the middle of the day.

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    Mute Jamie
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    Jul 31st 2017, 1:02 PM

    In the toilet

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    Mute Harry Corry
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    Jul 31st 2017, 1:08 PM

    @Jamie: That’s not surprising Jamie. It’s been quite obvious from your comments that you dwell in a toilet. Most trolls do…

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    Mute George Salter
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    Jul 31st 2017, 1:37 PM

    @Harry Corry: I thought trolls preferred under bridges? Or is The Billy Goats Gruff a myth like Santa?!

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    Mute mark kenny
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    Jul 31st 2017, 3:10 PM

    @Harry Corry:

    Just a thought,but why do people reoly to trolls?

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    Mute mark kenny
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    Jul 31st 2017, 3:18 PM

    @mark kenny:

    * reply

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    Mute @UK
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    Jul 31st 2017, 1:27 PM

    What’s a dining room?
    In open plan living/kitchen areas most people probably eat at the table in front of the telly

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    Mute Spilt Pint
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    Jul 31st 2017, 10:21 PM

    @UK; When I was growing up in our house we only really used it at Christmas. It was a room with a long table, sideboard for the china & silverware and a service hatch through from the kitchen. No TV or distractions and very old-fashioned.

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    Mute Alan Scott
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    Jul 31st 2017, 12:59 PM

    Mind your own business it has nothing to do with you

    62
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    Mute Sean Kelly
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    Jul 31st 2017, 1:09 PM

    @Alan Scott: I think your taking it a bit too literally. Its a poll. Don’t take it so seriously. For example I eat my dinner whilst on the jax in the middle of a cliffhanger. No need to be so aloof my friend…

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    Mute Alan Scott
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    Jul 31st 2017, 1:14 PM

    @Sean Kelly: Just a bit of fun Sean on a Monday am. Don’t take me to seriously I am sorry to anyone who might have the same view as Sean. I will try and conduct myself on the next poll.

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    Mute Louis Jacob
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    Jul 31st 2017, 1:21 PM

    @Alan Scott: now I really do want to know where you eat your dinner.

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    Mute Gordon Hughes
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    Jul 31st 2017, 1:21 PM

    In my mouth most of the time . But there is the occassional “10 second rule” applied to food that managed to hit the deck first

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    Mute Suzie Sunshine
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    Jul 31st 2017, 2:16 PM

    @Gordon Hughes: it’s a 5 second rule …

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    Mute Jho Harris
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    Jul 31st 2017, 2:31 PM

    @Suzie Sunshine: Not when you have a dog which makes it a split second rule.

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    Mute Suzie Sunshine
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    Jul 31st 2017, 2:58 PM

    @Jho Harris: lol very true !

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    Mute Joseph Bloggs
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    Jul 31st 2017, 3:40 PM

    @Jho Harris: well that’s just called ‘sharing’. But don’t let the dog get used to anything fancy. Don’t want them having notions because you dropped a bit of steak once!

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    Mute PaulOD
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    Jul 31st 2017, 1:32 PM

    Off a plate

    21
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    Mute Joseph Bloggs
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    Jul 31st 2017, 2:05 PM

    Slow news day.

    11
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    Mute Karl Bauer
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    Jul 31st 2017, 3:33 PM

    I haven’t eaten dinner in about 4 years. Decent breakfast, Decent lunch, at most a cuppa with a bit of toast at dinner time.

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    Mute Don Juan
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    Jul 31st 2017, 1:12 PM

    Standing up

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    Mute Rui Firmino
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    Jul 31st 2017, 1:45 PM

    tomorrow. “When do you usually poop?

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    Mute Thomas Maher
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    Jul 31st 2017, 3:03 PM

    @Rui Firmino: Between 6:30 am and 7am. Before I have to leave for work.

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    Mute Joseph Bloggs
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    Jul 31st 2017, 3:38 PM

    @Thomas Maher: not long after a coffee. Always greases the wheels.

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    Mute Rui Firmino
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    Jul 31st 2017, 4:40 PM

    @Thomas Maher: Me too!!

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    Mute Gerben Uunk
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    Jul 31st 2017, 2:48 PM

    Skipping dinner included too? Breakfast is most important meal of the day anyways. A healthy lifestyle vital ! Our mental body is in a constant Go-Go mode, but our
    physicial structure requires some rest too, and no foods are needed a small while before sleep, often its just so-called comfort eating.

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    Mute gerry fallon
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    Jul 31st 2017, 6:43 PM

    On my lap!

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    Mute Danny Halpin
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    Jul 31st 2017, 6:32 PM

    It should always be eaten in kitchen

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    Mute Shawn Rahoon
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    Jul 31st 2017, 4:24 PM

    In my mouth.

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    Mute Ronan Kealy
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    Jul 31st 2017, 6:10 PM

    On a plate.

    1
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    Mute Catherine Sims
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    Jul 31st 2017, 4:25 PM

    Don’t bother with dinner .

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    Mute Brian O Reilly
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    Jul 31st 2017, 4:09 PM

    Off of a plate

    1
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    Mute Quentin Moriarty
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    Aug 1st 2017, 4:19 AM

    In the attic with sandals and a crude candle

    1
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    Mute Johanna Donohue
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    Jul 31st 2017, 9:46 PM

    In the bathroom

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    Mute Ken Pepper
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    Jul 31st 2017, 7:40 PM

    On my penny farthing sashaying through dalkey

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    Mute Spilt Pint
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    Jul 31st 2017, 10:27 PM

    @Ken; I’d be curious to see someone sashay on a bike, it’s normally descriptive of walking/dancing.

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