Why did a Canadian town’s water supply turn pink?

Pink water. Image: Magic Momentz/Flickr/creative commons.

Most of us take it for granted that the taps in our homes will deliver safe and clean water for drinking, cooking, showering and cleaning. This means there is usually little interest from the public in how the water gets there. However, it took less than a day for a story from Onoway, a small town in Alberta, Canada, with just over 1,000 residents, to make it from social media to global newsfeeds. “Bright pink water comes out of taps in Canada!” – suddenly we are all interested in water treatment methods. The Conversation

To enjoy the benefits of clear and safe water, a hidden but valuable infrastructure of water treatment exists in our cities and villages. These are operated and maintained by engineers and scientists, and among them are water chemists. These chemists have been investigating the use of neat chemical reactions to remove undesired chemicals and potential pathogens from naturally sourced water and to prepare the water for its safe journey through distribution systems.

The local drinking water treatment plant of Onoway treats its water using potassium permanganate. This is an almost black looking solid which forms a bright purple solution in water and also removes dissolved iron and another metal called manganese.

Iron and manganese are not harmful to human health, but if these metals are present at high concentrations it can lead to deposits in the water distribution system and discolouration of the water. However, the auburn tints of iron seem boring compared to the spectacular pink that has raised global interest and lively social media discussions.

Customers are very sensitive to the colour, taste and odour of drinking water – these are the human senses used to assess water quality – so this incident has understandably caused alarm. The pink colour stems from some potassium permanganate that escaped through a failed valve and into the drinking water distribution system, eventually ending up with the customers.

Potassium permanganate has been used in drinking water treatment for more than 100 years. In addition to iron and manganese removal, it is used to remove taste and odour as well as to control undesired algal or mussel growth in treatment works. It also has disinfecting properties. Permanganate forms solid, black manganese dioxide when it reacts with the water contaminants – and this can then be filtered out of the water.


A little goes a long way

Potassium permanganate has the chemical structure KMnO4 and is a compound that is electron deficient – that is, it doesn’t have enough electrons. This lack of electrons makes it a strong oxidant that readily reacts with a wide range of unwanted compounds in water. It belongs to an established group of water treatment chemicals that can be summarised under the term “conventional chemical oxidants”, which also include oxygen, chlorine, chlorine dioxide, ozone, hydrogen peroxide and, in the wider sense, UV light.

Water is typically treated with a dose of 1-3mg of potassium permanganate per litre of water, which is quite a small amount. But only unreacted potassium permanganate has a visible pink colour in water and is visible even at very low concentrations – as low as 0.05 mg per litre of water – so it doesn’t take much to add colour.

Since only small quantities of permanganate can change the colour of water, customer complaints relating to residual permanganate are known to occur . This means treatment works usually take care to remove any unreacted, coloured permanganate before the water reaches consumers.

The pink water does not pose a threat to human health but skin irritation related to potassium permanganate is known at a certain concentration. Onoway’s mayor claimed that customers were not at risk. However, these concentrations seemed to vary – some had water merely tinted pink whereas some water was bright purple. Regardless of what shade of pink they receive, customers are advised to rely on alternative drinking water sources until the permanganate is flushed out of the distribution system.

Water treatment isn’t simple

For water treatment, there is no one-size fits all approach. Drinking water treatment processes vary due to different local water resources and what the traditional and established technologies are. Iron and manganese can be removed by alternative methods, such as aeration, which uses the oxygen present in the air, or by running the water over catalytic granules consisting of manganese dioxide. But every method has its specific advantages and disadvantages.

Many parameters need to be evaluated before making an informed decision on which method to use to treat a water supply – but there’s no doubt that potassium permanganate is one of the more colourful methods.

Jannis Wenk is a lecturer in water science and engineering at the University of Bath.

This article was originally published on The Conversation. Read the original article.

 
 
 
 

It’s not all cool bridges and very real concerns: In defence of Teesside

Just one of the many interesting bridges you’ll find in Teesside. Image: Stephen Jorgensen-Murray.

The latest entry in our ‘In Defence Of’ series...

I have to start this with a disclaimer: I’m not writing this from anywhere in Teesside. I’m writing this from Germany, where I live and work. Some of you may remember being told by Norman Tebbit, that instead of complaining that we can’t find jobs, we should get on our bikes (or, more recently, by IDS to get on a bus), and I did. I’m paid well here, to do a job that doesn’t really exist in Teesside. And yet, every time I go home to visit my family, I almost wish I’d stayed.

This isn’t going to be a very straightforward take – I’m hoping to pay my respects to Stockton, Middlesbrough and Hartlepool as well as my native Billingham – but Teesside isn’t a very straightforward place. What county is it in? Cleveland, Stockton-on-Tees, Durham or North Yorkshire depending on how old you are and where you’re standing. I always had great fun ordering online and trying to guess which of the unfamiliar options on the dropdown menu would get my parcel to me.

But regardless of where you draw the lines, Teesside is still there.

Our accent is similarly hard to pin down: Geordie, Mackem, Yorkshire, even Scouse, depending on who’s imitating us. I’ve been pegged as Irish, American and South African by determined people in the past. Our slang is stolen from Scotland, Northumberland, Newcastle and Yorkshire, and, not satisfied, some words are purely our own. Hoy, shan, howay, dinner nanny. We have as many words for classless people as the Romans did for murder.

But regardless of how it sounds to you, Teesside still talks.


On a map of the UK, Teesside sits as an isolated blob of civilisation between the Dales and the sea. Half-urban, half-rural, half-seaside, half-inland, half industrial estate and half nature reserve. A Labour heartland with a Tory mayor. Places that sprang up fully formed in the ICI rush of the 1950s, but that still have Viking place names.

We’ve been portrayed in fiction by Richard Milward, in song by Maximo Park, in statistics by Lady Florence Bell and in cinema by Sir Ridley Scott (our chemical works and power plants inspired the look of Blade Runner). More recently, we’re being portrayed in documentary in The Mighty Redcar, and in the media as an area of left-behind, white working class racists who all voted Leave. But while most of the area is whiter than the average, Middlesbrough mirrors the UK average for racial diversity and has been assigned to resettle more refugees than any other town in the UK – and more than its cut-back council can look after.

And when you look at the numbers, the proportion of the population of Teesside who voted to leave the EU is much less than many other areas. (And yes, of course I voted Remain from my now slightly more precarious home in Frankfurt, joining 100,000 other Teesside Remainers.)

We’re pitied for the loss of the Teesside steelworks and derided for blaming the EU for it (when of course it was our own government’s sabotaging of EU attempts to block Chinese steel dumping that drove that knife in). Even the people who profess to be on our side take our angry, uneducated racism as fact, baking it into the premises of their arguments, which consist of addressing our “racist but real concerns”, and how to reach us.

But whether you understand us or not, whether you miss the point or not, we’ll continue to exist, long after we’ve been forgotten again.

Billingham town centre. One of the first pedestrianised town centres in the UK. Image: Stephen Jorgensen-Murray.

Still, while we’re in the spotlight, why not see what we have to offer? Come to see our rather wonderful collection of interesting bridges. See where the first public steam train ran, from Stockton to Darlington. Visit Mima, the modern art gallery in Middlesbrough and the 1960s utopia of Billingham’s pedestrianised town centre. Feel slightly uncomfortable around all the things that are named for Captain Cook (though the replica of the Endeavour at Stockton riverside is impressive regardless on your thoughts on its captain – and it’s the best you’ll see until they work out whether they’ve found the real one yet). Wander Middlesbrough’s thriving student/hipster district on Linthorpe RoadD – despite being a punchline during my youth, Teesside University has become a respected institution. Visit Billingham’s Folklore Festival in August, where as schoolchildren we’d watch troupes of folk dancers from across the world open-mouthed, and get their autographs afterwards as though they were celebrities.

Fried chicken, white sauce and cheese make the Teesside parmo. Perfect. Image: Stephen Jorgensen-Murray.

Try a parmo. Try the Billingham Catholic Club’s real ale, and stay for the bingo, which is called by a man with the most acrobatic mental arithmetic skills I’ve ever seen. Try a lemon top ice cream from Pacitto’s in Redcar and wonder why no one else has ever done this before. Lemon sorbet and vanilla ice cream! Together at last!

While you’re at the beach, take a ride on the Saltburn Cliff Lift, the oldest operating water-balance cliff lift in the UK. Pretend Saltburn is sort of in Teesside while you’re enjoying the view. Look out on beaches black with sea coal, washed up from undersea seams and nearby coal mines. Visit the golf course by Seaton Carew to catch a glimpse of a curlew or two, and watch the young seagulls pick up golf balls to crack them open by dropping them from a great height. Visit Seal Sands, whose owners can be observed lazing on the estuary banks whenever the tide is out. Or visit Saltholme, the RSPB nature reserve, where you can see avocets, Britain’s weirdest-looking and most beloved seabird.

Nature coexists with industry on Teesside. Image: Stephen Jorgensen-Murray.

Go white water rafting, bell boating or paddleboarding at the Tees Barrage, where there are so many seals that they’ve had to put up guards to keep them out of the way. The Tees used to be too polluted even to support salmon and trout, and now we have too many of one of Britain’s largest native mammals. The return of the seals to the Tees was the first documented case of seals returning to an industrial area. You’d be surprised at how well nature can thrive in the shadow of industry, colonising the quiet fields and marshy ponds on private land that are never disturbed, haunted by sika deer and shelducks, redshanks, knots, stonechats.

Teesside has plenty to offer. What it doesn’t have is the jobs to keep its younger generations from having to get on their bikes and leave. We aren’t aliens, or Jacob Rees-Mogg’s army of goblin henchbrexiteers. We’re just like you, but with more seals and fewer employment opportunities.