Thursday 28 November 2019

Water: cleanliness is next to replicationness

I recently reported, couple of weeks late, our coliform=nope results. I could have popped them up earlier but they kept on getting bumped down the list by more immediate[-seeming] copy. That timing was okay because it means I can sweep in this rather lovely validation of those results.

One of our students has featured going to Dijon (let's call him D for Dijon) for his work experience because he had enough French to chat up the francophone Erasmus students in Food & Ferm Microbiology class last year. He is  also the poster boy for the New Irish: he has a really good tan, but on the telephone his accent would not hint at that, although his last name does. He's diligent, good fun, confident and kind and often willing to think [outside the box].  He contacted me a couple of weeks ago about the quality of the water at home in Dublin. He suggested that my current 3rd Year microbiology students might like to analyse a sample of his tap-water. Au contraire, j'ai dit, pourquoi ne pas vous faire des boites et faire l'analyse vous-même?  Then I found some appropriate, surplus to requirements, MacConkey and Nutrient Agar plates in the microbiology lab and saved him making up fresh - Win! And what might be wrong with D's water?

Irish Water, the government quango, is trying to deliver clean water and process the sewage safely for a whole country that is collectively unwilling to pay for this service. It is hopelessly, pathologically, under-resourced with its treatment plants operating at close to full capacity all the time.  Sooooo if there is a spill of rain that stirs up the sediment in the reservoirs, then the 'turbidity' goes over the limit and that treatment plant has to be switched out until the discolouration settles down. There's more to water treatment than keeping the coliforms and cryptosporidium out of our tap water. We kill the coliforms by dosing the water with chlorine but if the water is rich in discolouring peat residue then TriHaloMethanes THMs might be formed and these are potentially carcinogenic. This is not a desirable deliverable and modern treatment plants even have an automated cut-switch if the turbidity and THM risk gets too high. A couple of weeks ago, that spill of rain happened above a water-treatment plant in Leixlip in outer suburban Dublin. A spill of rain should come as no surprise in Ireland, but really there is no spare capacity. It didn't help that there was an operational failure on the cut-switch and thousands of tonnes of insufficiently-treated water shouldered past Leixlip and into the down-stream supply network . . . which serves 600,000 people across 4 counties.

Irish Water issues a boiled water notice to those those homes and premises to those usually served by Leixlip, although boiling does nothing for turbidity or THMs. I guess they are treating turbidity as a 'surrogate marker' for other sorts of contamination including coliform. Boiled water is grand for a family for a few days; a bit of an adventure even. But for a café it is an expensive inconvenience verging on disaster - imagine washing salad for 300 covers with bottled water. My correspondent M, who lives in the [unaffected] southside of the city, found it was impossible to buy bottled water anywhere in the city or county. I tell ya, when armageddon comes, neither water, nor bread, nor toilet paper will be obtainable the day after the Martians arrive on the White House lawn.

D is currently doing a final year research project, so it was dead easy for him to take 0.1 ml samples of water from home and spread them out on a few dozen Petri-dishes. I gave him a bottle of our water as a negative control - something known or strongly believed to be free of contamination. Two days later we were both reassured when D found no bacterial colonies had grown on any of the plates.

At about the same time (12 Nov 2019), Irish Water were given the all-clear by the EPA and Leixlip could start pumping good clean water to the public to end the Boil Water notice. "The ultimate solution is to replace the filters at the old plant and this process is being accelerated as quickly and safely as possible while still maintaining supply to the greater Dublin area. If we could, we would shut down the old plant, take it off line and do all the refurbishment at once. This is not possible because 20% of Dublin’s water supply comes from the Old Plant and we do not have the spare capacity to allow this to happen.” Creaking at every Victorian seam, leaking 50% of its treated water the Irish water supply is a money pit that nobody has the political ooomph to fix.

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