apologies if this has come up before. After reading about the need to boil water (at least the water I'll have access to) and downloading solar still plans I kept wondering why it needed that level of purification. Recently I've read posts and articles that say all that's needed is pasteurization...149 degrees. This jives with the composting I've done where the 160 degree pile kills all the pathogens. Are the experts coming to an agreement about this or is the issue in dispute?

-- Sand Mueller (smueller@brightok.net), November 17, 1999

Answers

The reason boiling is advised is because it can be easily seen and timed. Water can be sterilized at 150 degrees, but you have to be certain the water reaches that temperature and stays there for a required period of time. This method requires a good thermometer and a timer. I can't remember the length of time necessary, but it is considerably longer than if you just brought the water to a boil.

The inside of a car parked out of the wind can reach high temps even in winter. We plan to use ours as a solar dryer and solar oven. In summer the car definitely reaches a high enough temp to sterilize water.

-- helen (sstaten@fullnet.net), November 18, 1999.

WATER

A. What you need

A normally active person needs to drink at least two quarts of
water each day. Hot environments and intense physical activity
can double that amount. Children, nursing mothers and ill people
will need more. Store one gallon of water per person per day (two
quarts for drinking, two quarts for food preparation/sanitation).
And don't forget your pets need clean drinking water as well.

B. Water Treatment (Courtesy of FEMA)

There are 3 main methods for treating water, boiling, disinfection
and distillation. For additional methods of purification, contact
your local Red Cross.

1. Boiling

Boiling is the safest method of purifying water. Bring the water to
a rolling boil for 10 minutes, keeping in mind that some water will
evaporate. Let the water cool before drinking or storing. Boiled
water will taste better if you put oxygen back into it by pouring it
back and forth between two containers. This will also improve the
taste of stored water.

2. Disinfection

Before storing your water, treat it with a preservative, such as
chlorine bleach, to prevent the growth of microorganisms. Use
liquid bleach that contains 5.25 percent sodium hypochlorite and
no soap. Some containers warn, "Not For Personal Use". You can
disregard these warnings only if the label states sodium
hypochlorite is the only active ingredient; and if you use only the
small quantities in these instructions.

Add four drops of bleach per quart of water (or two scant
teaspoons per 10 gallons), and stir. Seal your water containers
tightly, label them and store them in a cool, dark place.

3. Distillation

Distillation involves boiling water and then collecting the vapor that
condenses back to water. The condensed vapor will not include
salt and other impurities. To distill, fill a pot halfway with water. Tie
a cup to the handle on the pot's lid so that the cup will hang
right-side-up when the lid is upside-down (make sure the cup is
not dangling into the water) and boil the water for 20 minutes. The
water that drips from the lid into the cup is distilled. Store as
directed.

-- spider (spider0@usa.net), November 18, 1999.

The issue is not in dispute.....pasteurization is an accepted method of purifying water.

Boiling is not only visable, but everyone knows how to boil water..... put it on the stove and let the bubbles begin. No thermometer needed. The solar pastuerizers are relatively new, and no one has much experience with them in this country. I mean, everyone has a pan, few people have a solar pasteurizer.

Yet, I've seen plans for large scale solar units, dug into the ground, and using a few sheets of plastic.

One problem is that no one has told the Red Cross, etc.that these things work, so that we get posts like the one above that only lists boiling and chemical purification methods.

-- de (delewis@XOUTinetone.net), November 18, 1999.