It's safe to drink from streams that the porters say are ok. You can Puritab the water if you want to, but the taste is ordinary unless you let it stand a good long while. I like Tang (orange or grape flavor) in my water when I use the tablets. If in doubt, use the tablets. Several of the main villages on the Moresby side have piped water which is safe to drink (Naduli, Kagi, Effogi one and two, Brigade Hill and Menari).

Don't drink too much or too little. It's easy to over-do or under-do the hydration. Carry at least 2 litres with you but not too much more. If desperate you can usually cadge a drink off someone.

Now, recently the issue of hyponatremia has come to light which is drinking too much water and washing essential salts out of you body which basically wrecks a lot of essential body chemistry and can be fatal. So can dehydration when walking in extreme conditions. You can google hyponatremia, and get the full story. It is common to get a white crust of salt on clothes from evaporated salts from sweat. You may choose to have your own supply of so-called energy drinks like gatorade or staminade or any of the others. Alternatively, pharmacists keep salt tablets on hand and give free advice. They are cheap and light to carry.

As well as hyponatremia, cramps can be a painful salts-related problem due to a magnesium defecit. But hey, if you are thirsty you gotta drink (as i explained to the barman). A problem is that a lot of the porters have been warned to make sure the white guys drink plenty and they are always encouraging everyone to drink at water spots. Mustn't blame the porters - they do the best they can. I take common salt tablets each morning on the track, mainly for cramps, which can hit at night or in the middle of the afternoon.

You can also google a 60 Minutes story about death on the Kokoda Trail. Extreme athletes have been aware of hyponatremia for years. It is not a new discovery, nor is dehydration.