I'm off this summer for 6 weeks of trekking across the Silk Road in China. I think it'll be an experience of a lifetime -- and an opportunity to take some great photographs. But that's not what I want to blog about today. Today's topic is: Purity of Essence .... errr... water (in a Strangelovian sense)
That is, in the nether reaches of the world, you're not always guaranteed to have fresh water. Even in Beijing and Shanghai, you're warned not to use the water from the hotel taps for drinking -- instead, boiled water in thermoses or spring water in sealed PET bottles is provided.
When I went to my travel doctor for the usual pre-travel battery of injections (HPA, HPB, DtP, tentanus, and influenza), he also recommended that I think about purity of water as well, since Western China is still developing. The main fears that I have about water are:
- Viruses: Hepatitis (even with vaccination, it's best to avoid exposure)
- Parasites: cryptosporadia and other protozoa, etc.
- Bacteria of all sorts
- Industrial pollutants: pesticides, heavy metals
When hiking in the American backcountry, I've usually relied on iodine tablets such as Potable Aqua or my little MSR filter. But my MSR filter (which didn't work against viruses such as Hepatitis) was lost in the Black Hole of Moving and Iodine doesn't work against Cryptosporadia. My doctor recommended chlorine dioxide tablets, but I noticed that it would take 4 hours of treatment before they killed all the little buggers.
Being a gadget-girl, I couldn't fail to notice the latest high-tech weapons race against ailments of the stomach and liver. (more after the jump)
Here are the various pros and few of the cons of water purifiers and filters:
|1l per 15 min (per tablet)||Dirt cheap, very portable||Doesn't kill protozoa|
Taste/color. Run out of tablets, run out of treatment.
|$5 for 30 tablets|
|Chlorine dioxide tablets|
|1 l per 15 min (viruses)|
1 l per 4 hours (protozoa) (per tablet)
|Cheap, very portable||4 hours to kill protozoa. Run out of tablets, run out of treatment. |
|$14 for 30 tablets|
|1.25l per min||Inexpensive||Bulky. Have to clean filters. Ones without iodine resin filters do not all catch viruses.||$60-100|
|Water bottle filter|
|0.3l per min||Inexpensive. Compact. Has iodine filter for viruses.||Have to clean filters. Limited capacity (0.3 liters/minute). New filter costs almost as much as the new kit ($40)||$40-60|
|1 l per 15 min (viruses)|
1 l per 4 hours (protozoa)
|Compact. Very sturdy.||Expensive. Relies on batteries (2 x CR123). 4 hours to kill parasites||$130|
|1l per 80 seconds||Compact. Very fast. Kills everything.||Expensive. Relies on batteries (Aquastar: 2 x CR-123A; SurPen = 4 x AA). Glass tube can break||$100-150|
(Note: For Americans: 1 liter is approximately 1 quart)
What I was mainly concerned about was purifying water in hotel rooms and public restaurants or on public transportation. In that context, chlorine dioxide or iodine tablets take too long. While they are great for base camps where you need a lot of water for cooking, I couldn't see using a manual pump in a bouncy bus or in a street market. The water-bottle filter seemed like a good option. But they have limited capacity and the filter price racks up over time.
The most elegant solution seems to be the UV lights which use a short burst of irradiation in the UV-C spectrum to disintegrate the DNA of microorganisms and viruses. They require about 30 seconds of treatment for 1 liter of water. There are two products on the market for travellers: The SteriPen and the AquaStar. More on them in the next blog entry.