Water supply and purification for emergencies

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Access the water

If a clear source of water such as rainwater, springwater or groundwater is used, this reduces the need for treatment, described below.
If there is a closer or cheaper source of water that is more polluted, this is still an option. This may have the advantage of lower cost and/or effort, providing a great benefit to those struggling in poverty. It must, however, be properly treated.
If using groundwater, check for arsenic, or at least do a proper analysis of the likelihood of arsenic contamination. The local geography and depth should give an indication. Arsenic contamination usually occurs when the water has spent many years underground in certain types of soil - for example, seeping from the Himalayas towards the Ganges delta. Thus it seems unlikely that arsenic contamination. See the Wikipedia article ^W for more. Keep it in perspective as well - fecal contamination is far more deadly and more a far more urgent problem than the levels of arsenic contamination normally found in groundwater.

Rough filtering, if the water is turbid (cloudy).
- On a very small scale, this may be done with a ^W.
- On a small scale, a small sand filter can be easily built using a bucket, sand and preferably gravel as well.
- On a large scale, slow sand filters are suitable where there is sufficient land area. Note that slow sand filters may be much more space efficient with suitable management, tilling the sand rather than scraping it, for maintenance.
Disinfection:
- chlorine or iodine tablets. A disadvantage is that people don't like the taste (particularly those not used to chlorinated municipal water supplies) and may fail to treat their water.
- Reduce the pH of the water - this is particularly suitable where cholera is a potential problem.^[1] (How effective is it against other problems? Is it a viable long-term solution, either at this level or more dilute?Template:Suggest project)

Water storage containers:

Water sources (^W).

↑ "...cholera survives far, far better at high pH than at low pH. In fact, in a few outbreaks [of cholera] in the 90s, the Centers for Disease Control was advocating that people put a lemon per liter in their water. Lowers the pH down to around 4 point something.That's roughly as good as chlorine at killing off vibrios [i.e. cholera]. Incredibly effective." Les Roberts, lecture 5 or 6 (on Rwanda), Water and Sanitation Needs in Complex Humanitarian Emergencies, in the Global Health course of the Johns Hopkins Bloomberg School of Public Health, available as OpenCourseWare (OCW). (Quote occurs at 13 min 45 sec ion the MP3 file.)

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