Denmark happens to be monumentally fortunate when it comes to freshwater reserves. For various geological reasons, which are beyond the scope of both my competence and this diary, we have an abundance of clean, subterranean freshwater. Even by fairly conservative estimates, we have enough water - and it regenerates fast enough - that it will last forever, if properly managed (which it isn't at the moment, but that is for another day).

This water is so clean, in fact, that it is possible to drink it almost directly out of the ground; it is no exaggeration to say that our tap water is cleaner than the bottled water you can buy in the supermarket (at, mind you, about a thousand times the price).

I am going to take you on a trip from the aquifer to the distribution pipeline, courtesy of the homepage of Ryomgård Vandværk.

The soon-to-be drinking water starts its career in an underground aquifer. From here, I will let the professionals take over:

   

Boringer og vandbehandling.		Aquifers and water treatment
Vandet hentes fra 2 boringer beliggende i tilknytning til vandværket på Ndr. Ringvej. Boring 1 er etableret i 1977/78 og er omkring 78 m dyb. Boring 2 er etableret i 1989 og er 74 m dyb.		The water is acquired from two aquifers located in close proximity to the waterworks on Ndr. Ringvej. Site 1 was established in 1977/78 and the aquifer is approx. 78 m below the surface. Site 2 was established in 1989 and the aquifer is approx. 74 m below the surface.
[...]		[...]
Vandbehandlingen på vandværket foregår i to parallelle trin. Fra boringerne ledes vandet over en iltningstrappe og gennem et sandfilter inden det tilledes en 500 m³ stor rentvandsbeholder. Herfra udpumpes vandet til forbrugerne.		The treatment of the water in the waterworks takes place in two parallel steps. From the drill sites, the water is poured over an iltningstrappe [1] and through a sand filter before it is transferred to a 500 m^3 freshwater container. From here, it is pumped to the consumers.

[JakeS Translation Technology]

That's it. The water is pumped up, oxygenated and pumped through a pile of sand. End of story. And we can actually get away with that, because we have very clean water and lots of it. Now, it occasionally happens that the water in an aquifer becomes polluted. Usually this is due to poor conduct one or two generations ago, and there is pretty much nothing to do about it other than move to a new drilling site.

But locating a clean aquifer and establishing a drilling site is expensive, so some municipalities would much prefer to simply add a cleaning sequence to the water treatment in the waterworks. That way, they would avoid the startup costs associated with exploring new aquifers. And, one might ask, what is the harm in that? After all, the technology is fairly readily available, it is only moderately energy-consuming, it doesn't really have any very nasty side effects [2] and it's already in use in most parts of the world.

This is where things begin to get complicated. Which, of course, is an euphemism for things getting political.

There are two main threats to the Danish drinking water doctrine:

• Excessive water usage. Water didn't use to be a problem. After all, there is more than enough groundwater, so we can just pump it at the rate we want to use it, right? Bzzzt, wrong, thank you for playing, we have some nice parting gifts. But old habits die hard, and Denmark does have some moderately serious water management issue. I will leave those, however, to people more competent than myself.

• Pesticides and fertiliser. If you spray toxic crap on your farmland, you get toxic crap in your groundwater. Alright, you won't see it for 30-60 years and you don't get a lot of it in the water - after all, most of it is broken down on its way through those 75-ish m of dirt. But you do get some, and once something is in the groundwater, it stays in the groundwater. For all practical purposes forever. If you spray nitrates and phosphates on your farmland, you get NOx'es and phosphorus in your groundwater. There are various reasons why this is undesirable (much the same reasons, I think, that you should steer clear of sausage with excessive nitrate preservatives [3]).

The second bullet is where the subject of this diary becomes political. Because there are two ways to solve this problem: The smart one; which is to stop over-fertilising and stop spraying toxic crap. And the "cheap" one, which is to clean the water in the waterworks. Now don't get me wrong, there is a certain amount of injustice in the system - municipalities today have to deal with the sins of our fathers. Not to mention our fathers' fathers. [4]

However, permitting municipalities to clean our drinking water would be a de facto (and virtually irrevocable) resignation of any commitment to clean groundwater. As such, a "pollute and clean" strategy will likely prove more expensive in the long term than a "don't pollute and don't clean" strategy. Not to mention the fact that chlorinated water tastes icky.

There is, of course, in principle no deterministic causal chain between adopting a pragmatic policy towards cleaning groundwater and a lax policy towards pesticide pollution and fertiliser runoff. (In the same way that there is no deterministic causal chain between US Republicans and New Orleans levee breaches or the I35W bridge.) So lest I be accused of committing a slippery slope fallacy, let me draw one fact to your attention that I consider rather important:

Today, Danish municipalities have an overwhelming incentive to ensure that their groundwater isn't polluted. Because they will eventually pay through the nose to finance prospecting for new groundwater reserves. They will have to pay because they cannot simply apply the band-aid solution of cleaning out the pesticide breakdown products. Now admittedly, the fact that there is a 30 to 60 year delay between the irresponsible policies and the penalty does put a damper on the effect of this disincentive. But I nevertheless do not think that it should be underestimated.

If, on the other hand, there is a (perceived) cheap solution to pollution problems, the incentives tilt heavily the other way: If a thinly populated municipality that is struggling to survive (because it is way below viable population density for a non-car-based society) has to decide between blowing the chance of getting a new factory farm and blowing the groundwater, I am betting that the groundwater will get the short shrift. Unless, of course, the city council know in the back of their heads that this particular chicken will come home to roost and force them to do a lot more inconvenient drilling.

So that's what it is about. I hope that I have convinced at least some of you that not cleaning our drinking water is not completely crazy.

- Jake

[1] I don't know the English term for this one, but it's one of these guys:

It's used to oxygenate the water, to permit trapped gases to evaporate and to permit metals and various salts that have dissolved in it to crystallise out. Many things dissolve more readily in the high-pressure aquifer than in an ambient pressure environment. Not only would they make the water taste bad, they might also clog up pipes if you don't get rid of them right away.

[2] Readers partial to the Scandinavian language might, however, find the reservations expressed here [.pdf] somewhat disconcerting.

[3] It's easy to identify: It's usually glow-in-the-dark pink.

[4] And our fathers' fathers' fathers