How to Filter Water Using Charcoal Sand and Gravel

You’re out on a nature walk and come across a river. You’re thirsty, so you reach for your trusty portable water filter of choice and realize that you have left it at home… you don’t know if the water is safe to drink. What do you do? One way to filter and purify water is by using charcoal, sand, and gravel. With this method, you can ensure the water is safe to drink, even in the wilderness.

Many individuals have trouble determining how to filter and purify water outdoors. It can be a problem if you’re hiking, camping, or even stuck at home during a power outage. Other methods of filtering and purifying water exist, but they may not be as effective or readily available.

If you’re wondering how to filter and purify water when you’re out in the wilderness, you’re not alone. Many people face this challenge every day. But with a bit of know-how, you can easily filter and purify water.

1. Method to Filter Water Using Charcoal Sand and Gravel

The correct combination of charcoal, sand, and gravel is an excellent way to filter and purify water. We can use this approach to guarantee that the water is drinkable in the woods. It will remove suspended contaminants, but will not remove all chemical contamination from the water if the water is heavily polluted, but it will be much safer than drinking water directly from the stream.

Required Materials:

You’ll need the following equipment to filter and purify water using this method:

•  A large pot or kettle
•  A way to heat the water (optional)
•  Charcoal
•  Sand
•  Gravel
•  A second container to layer the aggregate in

The steps for filtering and purifying water using this method are as follows:

1. Heat the water to boiling. You can do this over a campfire or stove.
2. Place the charcoal, sand, and gravel in the container.
3. Pour the hot water over the contents of the container.
4. Stir well and allow the water to cool before drinking it.
5. Purify the water by boiling it again before drinking it.

This approach is practical, but it does take some effort. If you don’t have the time, you may try one of the following alternatives.

Construction of the Sand, Gravel, and Charcoal Filter

There are two approaches to making a sand, gravel and charcoal filter, I personally prefer the layerd approach, it takes a little more effort but it gives a better filtration.

Method 1. The Layered Method

• Make a small hole in the base of the secondary container, if you have an old soda bottle make a hole in the cap, and cut the base off so that you have, what is essentially a long funnel. If you have a piece of material place it over the thread and screw the cap over to secure it. This will help keep the charcoal in place and prevent small parts of charcoal from getting through to the end drinking water. 
• Boil your charcoal in the pot to kill any contamination present on and in the charcoal. If you are taking the charcoal from a fresh fore then you can skip this.
• Crush the charcoal so that there is a mix of large, medium and small pieces. 
• Pour a layer ¼ the way up the container and tap it down so that it is even and firm but not too compacted. 
• Wash the sand to remove all debris then boil the sand for 5 minutes to ensure it is sterile. Place a layer of sand up to around halfway on the container. 
• Wash and boil the gravel then place just enough gravel over the sand to prevent the sand from being disturbed when you pour water into the container. 

That is it, now you can pour the potentially contaminated water into the top and you will get filtered water out the hole on the bottom.

Usually, the first few pours are a little cloudy and murky, but after a few washes through the fine dust will have washed through and you will be surprised how clear the water comes out.

Method 2. The Shake and Settle Method

I personally do not like this method and believe the previous layered style filter will give you a much purer product in the end. But this method is fast and simple, not requiring multiple washes and layerings.

1. Prepare your container in the same way as step one above. 
2. Wash the sand and gravel as best you can. 
3. Place  Charcoal, Sand, and gravel in the pot with a ratio of 4:2:1
4. Boil all the filtrate to kill pathogens.
5. Fill the container ⅔ full with the filtration materials. 
6. Place your hand over the hole and fill the container with water.
7. Using your other hand cover the top and shake vigorously, trying not to let any of the mix escape. 
8. Hold the container vertically letting the material all settle then remove your hand and allow the water to filter through. 
9. Pass a few washes of water through, when you get clear water you are ready to use the filter. I will say it again I personally do not think this is the best way to build a charcoal and sand filter, but it is still effective, so give it a go and see the results for yourself.

Method to Filter Water Using a Coffee Filter

It is unlikely you just happen to have a coffee filter with you when out in the wild, unless you were smart and planned ahead. Coffee filter papers are well worth packing into your pack as they are light, take up no space, and are a fast effective way to remove particulate contamination from water.

You should boil the water to kill bacteria but after it is boiled it will be free of particles, pathogens, and bacteria. Heavy metal or chemical contaminants will remain, but in most cases, these are not present in wild streams unless they are down from some sort of industrial or mining activity.

You’ll need the following equipment to filter and purify water using this method:

• A coffee filter
• A container
• Some gravel 

The steps for filtering and purifying water using this method are as follows:

1. Place the coffee filter in the container with a few large rocks or gravel to hold it in place.

2. Pour the water over the coffee filter.

3. Allow the water to drip through the filter into the container.

4. Boil the water before drinking it.

Can You Filter Water With Rocks and Sand?

Yes, you may filter water with rocks and sand. This technique is frequently used outdoors to purify drinking water.

Is It Possible to Filter Water With Sand?

Yes, you may filter water with sand, but it will only remove large particles and will not remove bacteria.

What is the Best Way to Filter Water Using Gravel?

Gravel can be used to filter water by trapping impurities and contaminants. The larger the pieces of gravel, the more effective it will be at filtering water.

Is it Safe to Drink Filtered Water?

Yes, it is safe to drink filtered water. However, you should always boil the water before drinking it to be safe.

What Are the Benefits of Filtering Water?

The main reason you want to filter water when in the wild is to remove foreign matter and improve the taste, the boiling is to kill nasty bacteria.

Conclusion:

So yes it is possible to make a makeshift water filter using charcoal, sand and gravel. While this may work in a pinch, it is not as effective as a lifestraw or other portable filter and should only be used as a last resort. If you want to see a list of the best portable filters you can see them all here in our best portable water filters section.