Saturday, April 14, 2012

Dirty Water and How to Easily Clarify Before Ceramic Filtering

Water is absolutely critical to survive more than a few days. Knowing how and where to get clean and safe drinking water is something we all must know now before we need it.

There may be times when clear water is not available such as after a disaster including major flooding or when backpacking or canoeing into remote areas. Ceramic filters can filter out the turbid and muddy particulates in the water but those particles will quickly clog the ceramic filter. For the best performance from your ceramic filter it is best to start with clean/clear water first but how can you cheaply, quickly and easily do that?

It’s called ‘ALUM’ (Aluminum Sulfate) a safe powdered chemical commonly used for removing cloudiness in swimming pool water. It is also used in cooking, pickling and used in some types of baking powder. Note, ‘ALUM’ does not purify the water; it only removes the suspended particulates. You must filter the water through a ceramic filter before drinking.

How does ‘ALUM’ work?
Murky, muddy, cloudy or turbid lake or river water is caused by microscopic particles usually 1 micron or smaller that river currents keep stirred up. Gravity has little effect on them because they are too small to have enough weight to settle out by themselves. These tiny particles have a negative electrical charge that prevents them from being attracted to one another thereby prevents their clumping into a heavier particle that will eventually have enough weight to sink by themselves.

When ‘ALUM’ is added to the water it neutralizes the electrical charge of these small particles and then these small particles will begin to clump together, become heavy and sink to the bottom. This process is called flocculation also called coagulation.

How to use ‘ALUM’ to clarify water:
1. Add a heaping ½ teaspoon of ‘ALUM’ powder per gallon of water (1 tablespoon for 5 gallons of water).
2. Stir for about 10 seconds to dissolve the ‘ALUM’ and in about five minutes stir again.
3. Wait for 1-2 hours and the water will be clear and ready to pass through your ceramic filter. Just dip the water out or carefully pour the water out and into your ceramic filter. That’s it!

Where can you buy Alum?
You probably already have some in you spice rack.

Supermarkets sell it in the spice section, although it is very expensive at $3.00 for 2 ounces.

Any online bulk spice retailer such as:
5 pounds will clarify 630 gallons of water or 126, 5 gallon buckets of water.

Search the web for other retailers, there are many to choose from. Just be sure you purchase food grade ALUM and not an industrial grade that may have other chemicals added to it. The swimming pool industry uses ALUM to clear up pool water and it could have additional agents in it. This is why I buy it from spice companies.

ALUM from the supermarket. A 1.9 oz jar is expensive at $3.00 but will clarify 15 gallons of water (3 tablespoons in 1.9 oz).

Since I don’t have turbid water close by for the test water I scooped up some dirt from my yard and mixed and the ALUM into a gallon of water.

2 hours later this is what it looks like. Just skim off the floating leaves and junk then pass through the water filter.


  1. Great info Mike. I will be getting some Alum right away. I had been thinking my ceramic filters were going to get very dirty very quickly when using creek or lake water. The Alum will be a good pre-filter step. In all the research I have done on filtering water I have never seen anyone mention this or anything like it. Thanks again for this very good info.

  2. Wow, very interesting. I never knoew I could use alum for clarifying water. I have some in my cupboard that I have used when making pickles, but really I don't use it. Now I know what to do with it.

  3. In aquaculture egg whites (albumen) s used as a flocculant for waste solids. It might help with at least the larger particles. Just mix the whites with a small amount of water to break it up then add to your bucket. Typical dose is 1 egg per 1000 liters of pond water so might be a good idea to experiment for smaller

  4. Notworthy,
    That's very interesting, thanks. I'll have to look into it.

    1. Question Mr. Yukon...Does the water need to be sterilized after the filtering?

    2. After passing the water through a ceramic filter there is no need to sterilize or boil the water. It is ready for drinking and cooking.

  5. Great info. I just made a play-doh recipe that called for Alum. I didn't have any on hand, but will plan to add this to our pantry.

  6. Alum is also great for cold sores...dries them right out...careful not to taste!!

    1. Thanks for the tip. I'll have to research that as it could be very handy to know.

  7. Is the aluminum filtered out? Because if not could that not be a significant amount to be drinking? I avoid aluminum in baking powder, deodorant, etc because it accumulates in the body and causes health issues so I'm wondering what the implications of this would be. Thank you

    1. Using Alum this way is to collect all the suspended particles and make them heavy so they sink to the bottom of the container thereby clearing the water making it ready for filtering. The ceramic filters may remove the aluminum. Check with the filter manufacturer for advice. I personally don't care about the aluminum content as this water is for disaster emergencies and may be all I have to survive on. Hope this helps.

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  9. It also works as an acceptable blood stauncher. I use it when we nick the dog's vein cutting his nails. Great addition to the toolkit!


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