# Purifying water at home **URL:** \ **Category:** Factual Questions\ **Created:** [October 21, 2009, 12:31am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543 "2009-10-21T00:31:40Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [October 21, 2009, 12:31am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/1 "2009-10-21T00:31:40Z")
Actually, I’m teaching Environmental Science, and I’m wondering what we can do to treat dirty water. A bleach shock should get rid of biological concerns, and activated carbon should do a decent bit. I’ve talked to a salesman from a reverse osmosis company, though, and he said that we still won’t have dealt with heavy metals or petroleum products. Does anyone know of something more homegrown than RO that would remove these types of things? I’m trying to be cheap just for the money, and also show kids something commonly available and practical. ---
**Author:** ![Haunted](https://avatars.discourse-cdn.com/v4/letter/h/898d66/32.png) [@Haunted](https://boards.straightdope.com/u/Haunted)\ **Post date:** [October 21, 2009, 1:07am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/2 "2009-10-21T01:07:03Z")
It looks like even Clorox says that boiling is best for killing parasites and microbes. I suppose the choice to boil or to use bleach depends on what you have: fire/electricity or bleach. > **[Emergency Water Purification Calculator](http://www.csgnetwork.com/h2oemergencypurifycalc.html)** > > In an emergency, to purify drinking water, two methods are most often used. ---
**Author:** ![mswas](https://avatars.discourse-cdn.com/v4/letter/m/e99b99/32.png) [@mswas](https://boards.straightdope.com/u/mswas)\ **Post date:** [October 21, 2009, 1:14am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/3 "2009-10-21T01:14:58Z")
Run it through a filter that has a layer of charcoal, sand, and cloth. Then you can use ozone from a tesla coil to kill bacteria. 😉 Or you could boil it. 😉 ---
**Author:** ![boytyperanma](https://avatars.discourse-cdn.com/v4/letter/b/4491bb/32.png) [@boytyperanma](https://boards.straightdope.com/u/boytyperanma)\ **Post date:** [October 21, 2009, 1:45am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/4 "2009-10-21T01:45:50Z")
Distill it ---
**Author:** ![Superhal](https://avatars.discourse-cdn.com/v4/letter/s/b4bc9f/32.png) [@Superhal](https://boards.straightdope.com/u/Superhal)\ **Post date:** [October 21, 2009, 2:00am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/5 "2009-10-21T02:00:08Z")
I’ve been using the Pur system for years, and the holder for the filter costs about $10, the filters (3 stage, I believe) cost about $10-20 each. I don’t think you can make an effective system from scratch cheaper than that. ---
**Author:** ![Nars\_Glinley](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nars_glinley/32/8177_2.png) [@Nars\_Glinley](https://boards.straightdope.com/u/Nars_Glinley)\ **Post date:** [October 21, 2009, 2:08am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/6 "2009-10-21T02:08:59Z")
> [@Superhal](#): > > I’ve been using the Pur system for years, and the holder for the filter costs about $10, the filters (3 stage, I believe) cost about $10-20 each. > > I don’t think you can make an effective system from scratch cheaper than that. Do any of the filters kill bacteria? ---
**Author:** ![Superhal](https://avatars.discourse-cdn.com/v4/letter/s/b4bc9f/32.png) [@Superhal](https://boards.straightdope.com/u/Superhal)\ **Post date:** [October 21, 2009, 2:21am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/7 "2009-10-21T02:21:57Z")
> [@Nars\_Glinley](#): > > Do any of the filters kill bacteria? Interestingly, the Pur website neatly sidesteps that question by posting a bunch of water bourne bacteria, but never claiming if the filter removes them. However, I did find this article about homemade filters: [http://www.woodcraftwanderings.org/water.html](http://www.woodcraftwanderings.org/water.html) ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [October 21, 2009, 2:24am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/8 "2009-10-21T02:24:45Z")
> [@mswas](#): > > Run it through a filter that has a layer of charcoal, sand, and cloth. Then you can use ozone from a tesla coil to kill bacteria. 😉 Or you could boil it. 😉 I’m aware I can bleach it or boil it, guys (plural). I specifically asked about the petroleum products and heavy metals. And we already did coffee filters/sand/activated charcoal/clean old t-shirt. That worked pretty well, but as I say, supposedly this misses two categories. ---
**Author:** ![Cardinal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cardinal/32/4000_2.png) [@Cardinal](https://boards.straightdope.com/u/Cardinal)\ **Post date:** [October 21, 2009, 2:31am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/9 "2009-10-21T02:31:36Z")
I did visit that link, but the author mentions that “chemicals, pesticides, and heavy metals” can be removed with activated charcoal, then provides no list or examples in any way. I did find this list: [http://www.buyactivatedcharcoal.com/poisons](http://www.buyactivatedcharcoal.com/poisons) but it’s from a site wanting to sell me the product, and of course it doesn’t mention what it misses. ---
**Author:** ![even\_sven](https://avatars.discourse-cdn.com/v4/letter/e/dfb087/32.png) [@even\_sven](https://boards.straightdope.com/u/even_sven)\ **Post date:** [October 21, 2009, 2:33am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/10 "2009-10-21T02:33:37Z")
To purify water with industrial pollutants, you need to distill it. I use a home water distiller here. It’s broken right now, so I’ve been boiling, and there is a thick layer of horrible scum building up on my water pot. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [October 21, 2009, 2:42am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/11 "2009-10-21T02:42:59Z")
Make a solar still. Simple and effective - > **[Solar still](https://en.wikipedia.org/wiki/Solar_still)** > > A solar still distills water with substances dissolved in it by using the heat of the Sun to evaporate water so that it may be cooled and collected, thereby purifying it. They are used in areas where drinking water is unavailable, so that clean water is obtained from dirty water or from plants by exposing them to sunlight. > Still types include large scale concentrated solar stills and condensation traps. In a solar still, impure water is contained outside the collector, where it is evaporated by ... ---
**Author:** ![Alex\_Dubinsky](https://avatars.discourse-cdn.com/v4/letter/a/dbc845/32.png) [@Alex\_Dubinsky](https://boards.straightdope.com/u/Alex_Dubinsky)\ **Post date:** [October 21, 2009, 3:32am UTC](https://boards.straightdope.com/t/purifying-water-at-home/514543/12 "2009-10-21T03:32:05Z")
Plus kids can find so many other uses for distillers…