Until a lot of people got sick in Havelock North last year I'd supposed every town in New Zealand had chlorinated water. Why wouldn't they? It's one of the things that distinguishes even modestly advanced countries from the Third World. We can confidently tell tourists it's safe to drink the water.
The truly surprising news from Havelock North for me was not that a microbe had got into one of its bores but the number of places that do not disinfect their water, including one of the main cities, Christchurch.
It's a strange city, old-school English but fiercely provincial, leftish in thinking and given to eccentricities. It doesn't fluoridate its water either.
Growing up there, I knew the artesian water came well filtered by the gravel under the thin topsoil of the plains but had no idea it was not treated, and I suspect not many Cantabrians knew. Now though, the purity of their water has become another point of parochial pride.
They insist it tastes better than the water anywhere else. The bottling industry seems to agree, quite a number claim their water comes from wells near Christchurch. But when I visit family there I'm damned if I can detect anything notable from the tap.
Yes, of course I still drink it. Initially I was annoyed to discover I'd been drinking untreated water down there but then didn't give it another thought until the inquiry into Havelock North's gastroenteritis outbreak produced its wider report this week.
The report attempts to make a case for compulsory treatment of all tap water in New Zealand. "Pathogenic microorganisms are found everywhere," it warns, "complete protection is impossible and further barriers against contamination are vital."
Waterborne disease often arise, it says, after events such as heavy rain and flooding, droughts or power failures. In a section that might have been written especially for Canterbury, it notes advice from GNS that, "earthquakes pose a particular risk and have the potential to compromise the integrity of wells and reservoirs, alter the flow of an aquifer, cause an aquitard to fail and damaged piped distribution systems."
That risk is nationwide. GNS reckons large earthquakes can alter the state of aquifers hundreds and even thousands of kilometres from the epicentre.
For these reasons and more, the inquiry team recommends all water supplies be treated and supervised much more assiduously.
It recommends a set of standards to be enforced by a new national agency instead of local councils that it finds vulnerable to popular pressure. As engineer Iain Rabbitts, one of the inquiry's advisers, put it in the Herald yesterday, "If the Mayor of Christchurch, Lianne Dalziel, didn't fight against the chlorination of Christchurch's water she would possibly lose the next election."
It will be interesting to see how the new Government handles this one. Labour abhors a regulatory vacuum. Environment Minister David Parker sounded particularly shocked to read that not one compliance order has been issued by the Ministry of Health. But the Greens probably sympathise with those who see no need to put chemicals in water and think contaminants can be kept out.
With luck, nothing will happen. When something goes wrong it is very hard to retain a sense of proportion. A committee of inquiry takes a long time and a lot of work. They never produce a report that says, "All things considered, especially the rarity of this sort of event, we do not think it worth the expense of a higher level of protection."
Instead, we have to strengthen old buildings or knock them down in case of an earthquake unlikely to happen for hundreds or, more likely, thousands of years. And Havelock North might result in a new government department with an army of inspectors throughout the country to oversee a job municipal councils appear to be doing well enough.
Given how easily faecal microbes can get into groundwater, "anywhere there are people, pets, livestock, birds or wildlife", the report says, it is telling that we do not hear of an outbreak every year.
The report says, "Experts have estimated that in addition to mass outbreaks, between 18,000 and 100,000 sundry cases of sporadic waterborne illness occur every year."
An estimate that wide looks like speculation.
But even at the high end, the number is not alarming when you consider how many people get sick for a day or two every year. And whether the nasties come by water or air, we are talking tummy bugs here, not the plague.
Councils who think they can get away without chlorination have seen what happened in Havelock North. But even there, some residents are still protesting against chlorination. If enough voters in those unfortunate localities don't want treated water, good luck to them. I'm just glad to live where good sense prevails.