Does boiling water make it safe to drink?

Monday, July 31, 2006
A camping trip is a great way to immerse yourself in nature and try to exist as basically as possible, literally living off the land. And no camp is complete without a cup of billy tea made from fresh stream water.

But as much as stream water often looks perfectly clean, most of us would probably boil it before drinking it just to be safe. But is this really the right thing to do? Our reporter Michael Slater finds out.

Michael tells Graham that he's just got some water from the river and is trying to make a cup of tea. By boiling this water is it going to be safe for him to drink?

"You hear that around a lot. But I'm a bit suspicious of boiling water and how effective it is," he says.

So what are we trying to get rid of when we boil the water?

"There's a whole range of things. There's certainly a bunch of parasites or some people call them protozoans. There's bacteria, nasty viruses and there's all sorts of other toxins that can be in the water — you can't tell by looking," says Graham.

Sometimes there's no choice what you drink. Julie and Paul got lost on a bushwalk, and found themselves drinking from puddles in a creek bed — not good.

"Just started getting a really weak stomach, and feeling like I couldn't eat as much food as I normally would and ended up running to the toilet all the time," says Julie. Paul suffered from diarrhoea and feeling sick in the tummy.

It sounds like Paul and Julie copped a dose of cryptosporidium — parasitic little cysts carried in animal dung. Swallow contaminated water, and they'll hatch and multiply in the walls of your bowel.

The same little mongrels had Sydneysiders boiling their water during an outbreak in 1998. A good hard boil has been shown to kill cryptosporidium. But what about other nasties?

How can we be sure our billy water is safe to drink?

Michael is off to speak to the experts at the University of New South Wales.

Professor Brett Neilan is a top microbiologist, he'll compare a boiled and a non-boiled sample of Michael's billy water under a microscope.

In the non-boiled sample there's quite a lot of bacteria in one little drop of water — amazing.

In the boiled water, there is still a lot of debris in the water, which could be dead cells.

The boiling has cooked the crypto and other bugs, but if we think it's clean now, we're in for a nasty surprise.

Remember the world's biggest blue green algae outbreak back in November 1991? A 1000-kilometre stretch of the Barwon and Darling Rivers was covered by a deadly bloom. Some blue green algae toxins are 200 times more toxic than cyanide!

And guess what? Not only did Michael have them in his water sample, but the boiling actually released the toxins into the water!

"It's the second most potent toxin known to man. It's actually listed by the World Health Organization as a chemical weapon. So you could have done some danger to yourself Slats," says Professor Neilan.

"In looking at that [under the microscope] I was better off drinking the raw water. We are dispelling a myth here," says Michael.

The good news is that filtering can remove the nasty toxins.

To show Michael, Brett trickled really poisonous blue algae water through some ordinary river sand.

"And you can see at the end of that experiment there was clean water coming through. Which is almost ready to drink," says Professor Neilan.

So what is the best way to clean up your water when you're in the bush?

Survival expert Graham has got it all worked out. He's got a few tricks to try. One of the simple ones is hydrogen peroxide. Most of the nasty things that hate us hate oxygen, so this goes some way along to encouraging them not to do us any damage. All you need to do is add up to 10 drops of that to a litre of water.

Once the chemicals are in Graham says to filter it. How? Easy. Tie off the bottom of some sacrificial jeans. Grab some cold charcoal from the fire and pop it in. Then, pour the water through it.

"Almost any toxin we put through here [the filter], carbon will combine with it, capture it, and keep it in the filter as long as you've got charcoal in there," says Graham.

Graham's three-stage water treatment:

  • Chemicals to beat the bacteria.
  • Charcoal to filter the toxins.
  • A good hot fire will take care of the rest.

Also, you can relax, you don't have to cut up your favourite duds — portable water filters are available at good outdoors stores.

Well, it seems boiling water to make it safe is certainly a good idea. It will get rid of a lot of the bugs that lie beneath, but what it won't do is get rid of the toxins that the bugs produce. So whenever you're drinking water from a natural source, it's a good idea to filter it before you boil it. It may save you a lot of pain in the long run.

  • In Australia we take clean safe water from the tap pretty much for granted. But around the world, more people die from diseases contracted through unsafe drinking water than any other illness: 1.7 million people a year.

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