Why would I need to purify water?

It’s been suggested that we keep a minimum of three days worth of water around. But now, many government agencies – the WHO, FEMA, Ready.gov – are suggesting that we keep a minimum of two weeks. At a gallon a day that’s roughly 14 gallons of water per person.

What happens when that runs out? There will be a need to discover water sources as well as a need for developing them. We’ll talk about developing later.

Two water sources

There are two immediate sources for water. One is surface water, which is always suspect; you must consider surface water to always have impurities in it, to have viruses and diseases in it. The other is groundwater. It’s not always as bad as surface water; however, the potential is there. So you need to take precautions where both are concerned.lake pollution

Wee beasties

As much as it would be fun to impress you with my vocabulary of all the wee beasties that are in the water, the thing to understand is that there is stuff in that water that at best would just make you sick. The majority of the viruses and diseases that are in tainted water will indeed make you extremely ill, increasing the potential of death, especially in those that are in vulnerable situations as it is: children and the aged, and even ourselves. Don’t just point your finger to others!

We really need to consider that every water source that’s out there will have something bad it. There will be parasites. There will be viruses. There will be diseases. There’s a lot of bad stuff in water.


There are viruses. Viruses, as defined by Merriam-Webster, are extremely small living things that cause diseases and that spread from one person or animal to another. A disease or illness caused by a virus is called a viral disease.


Parasites are another thing that we have to consider in our water source. They are little things that attach to the insides of our stomachs and our bowels so they can feed off of us; we become the hosts. In doing so, their waste matter is what typically causes the greatest problems within our bodies.

There are four steps to get rid of these. The first is coagulation. The second is sedimentation. The third is filtration. And the last is disinfection. When we’re finished with all four of the steps, the water becomes safe to drink.

Purifying water in municipalities

water coagulations with alum

Coagulation and sedimentation

Coagulation and sedimentation take place at the same time. During the coagulation method that our municipalities use, they get raw water which has all kinds of debris in it and they introduce alum to the water. The alum will surround the suspended particles that are in the water (these are the ones that are not settling to the bottom or floating to the top). When they surround the particle, they draw it to the bottom, which is the sedimentation process taking place.

sedimentation water filtering process

Filtration and disinfection

After they drain the water off the top of their large tanks, it goes through a filter. Once the filtering process has finished, and they’ve taken large floating bits to tiny, tiny things, the disinfection process takes place. Most municipalities use a chemical process where they add chlorine and/or ozone to it.

There are several other methods that municipalities like to use. Most of these are based on economy more than anything else.

Purifying Water at Home

In the home water-purification process, coagulation is not something that you’re likely to want to spend time and effort on. This is because sedimentation and filtration are going to get rid of the most important things. It just takes a little longer.

For personal, immediate water needs . . .

You should anticipate your water needs long before they become dire so that you have plenty of water on hand to take you through a few days while you find a water source and begin your process. Don’t think your swimming pool is the answer. Some of this will take a little time, and a lot of it depends upon the amount of water that you’re trying to purify. You should also store as much water as possible.



Now, let’s get back to sedimentation. First get your water and put it into a large container. Then, let it sit for a minimum of 24 hours. This will allow most everything to settle to the top of sink to the bottom. Take it out of the weather if at all possible; keep it in a shady spot; keep the wind off of it – these things do affect the water because they will keep it stirred up.

You also want to keep any animals from being able to have contact with the water at this stage because it’s time to purify it and clean it for yourself. So, as you let it sit, it will separate; most of the solids will go to the bottom. There will be organic debris that will float to the top, and that can be skimmed off.

A good way to see that your water is ready for you to send through the filter is if you put the water in a clear two-liter soda bottle. Set the soda bottle on side. Placing it on news paper, magazine and the like. Something that’s about a 12- or 14-point font. If you can read through the bottle of water, then your water is clear enough that you can send it through your filter. It could go through before this, however it will shorten the life of your filter.


Next, after sedimentation, you go through the filtration process. There are a couple of ways to do this. Gravity is going to be the best way; instead of using pumps and agitators like our municipalities use. You can either purchase a commercially-made filtration system to put your water through, some have a significant cost, or, do it yourself. There are many do-it-yourself methods; I’m going to share two of them with you.

Materials (medium) checklist

The filter needs to be made up of a few elements, each in equal parts. The first one is pea gravel; imagine something the size of your small fingernail or smaller. Then you want sand, washed and sanitized. And then you want charcoal. Now, don’t think you can go out and purchase commercially-made charcoal briquettes. There’s additives to those that you don’t want in your body from a drinking standpoint. It is possible to make your own charcoal from wood. If all you have access to are the briquettes, then that’s what you should use, but I do not recommend it.

Two-Bucket Filter

The first method is with two buckets, one bucket being larger than the other. First penetrate the bottom of the smaller bucket with holes. Then in the larger bucket, put a layer of charcoal, and set your smaller bucket down on top of that. Then put the rest of the charcoal in the outer bucket, taking it up to about a third of the side. Then you fill in with sand, on top of that, the pea gravel.
two-bucket-filtrationLooking at the diagram, you’ll see that you’re not putting these mediums in the inner bucket. You’re putting them around the inner bucket.

Next, simply pour your water into the outside ring of the outer bucket. As the water slowly trickles down, it percolates through the gravel removing large material, then through the smaller sand material, and then through the charcoal, which gets the really small stuff. Sometimes, you can filter out the viruses. Sometimes, you cannot. What you’re doing is making the water as clear and clean as possible. Remove the clean water from the small inner bucket with a dipper or ladle.

Now, consider that as you put water through the filter, eventually, the filter becomes clogged. You will know this by how slow the filtration process takes. So you will need to discard those have a source where you can discard those and start off with clean fresh medium. It’s up to you.

Traffic Cone Filter

A quicker filtration system uses a traffic cone. The same as the Two-Bucket method just inside out. Turn the traffic cone upside-down, then put a piece of screen or a piece of fabric at the bottom, in the neck of the cone. Then place charcoal a third of the way up your traffic cone. Then fill another third of it with sand. And the final third is filled with the pea gravel.

traffic-cone-filtrationPour the water through the traffic cone and catch it in another basin. You cannot use the same basin that you used with your impure water: it is impure! Things that become tainted will stay that way until you get access to soap and boiled water.

Now, the traffic cone system is a little bit faster, but you’re using less filter medium, and the quantities of filtered wee beasties are different. So the water you’re going to end up with is still very suspect.

The goal of filtration is to remove all of the solids from your water so that viruses and diseases can’t attach to them and the water will not be affected by chemicals or by other methods of disinfection that we’re about to talk about.


Once the water has gone through the filter, it’s time to do the disinfection process. This is really kind of fun. There are about three or four different ways to do this. We’re just going to talk about the three that I know best.


The first one, and quickest, of course, is going to be to treat your water with chemicals; meaning common household bleach. What you’re looking for is the stuff at the dollar store, but you need to double-check and read the label and make sure that it is at least a 5% solution. Anything less than a 5% solution may not do the complete job.

The correct ratio is about 16 drops of bleach to one gallon of water, or about a quarter teaspoon of bleach to a gallon of water. Let it sit for a while, then stir it gently. Let it get where the impurities that are in it will have time to be destroyed by the chlorine. Stir it occasionally. After a 12-hour period, the water should be disinfected.

There are other chemicals however, there is a greater expense with these. Keep it cheap, you’ll need to purify a lot of water.


The other way is simply to boil the water. You need to bring the water to a rolling boil for between a minimum of one minute and a maximum of seven minutes (there are different schools of thought on the time). Boiling is at 213 degrees Fahrenheit, and most things that will harm us die before they reach the 213-degree mark. You want to make sure that all of the water in the pot gets to 213 degrees. Hence a rolling boil.

After you boil the water, and it begins to cool, you need to pour it from beaker to beaker to aerate the water. When we boil water, it gets a different flavor, so we aerate it to help that.

Sunshine (UV rays)

This last way is a simple and passive a way to disinfect your water. Pour the filtered water into clear plastic water containers that are covered and are not open to the atmosphere. Place them in as sunny a spot as possible. Allow them to sit in the sun for 24 hours.

Now, I realize that if the sun goes down, it’s not there. But what you’re trying to do is to maximize that ultraviolet radiation, which kills the bacteria, the viruses, and the parasites that you have not been able to filter out.

Clean, clear containers

The rule of thumb is that if a two-liter bottle is scratched, and you can’t see through it (in other words, it’s just simply opaque), it’s probably not going to be the best. It can be used in an emergency; however, the best thing to do is keep containers that can be used for UV disinfection for that purpose. Then pour that water into other containers to keep and store it.

Filter. Disinfect. Repeat.

This should be an ongoing process. It shouldn’t be something that you do once or twice and think that’s going to be sufficient. This should be something that you take a little time to do every day so that there’s always plenty of water. It’s better to have too much than not enough.

And that is how you purify water.