We know that water filters help to turn dirty water into a refreshing, drinkable liquid. They can remove nasty things like dirt, bad smells, and bugs that could make us sick. You might even have a water filter in your kitchen right now!
But how do these water filters actually work, and are they all the same? Below, we’ll find out about the main types of filters found in homes around the country. We’ll look at:
- What these water filters are called
- How they work
- And what kinds of common water contaminants they filter
1. Carbon filters
Carbon water filters are the most common type of water filter. You can find carbon filters in refrigerators, attached to taps, and inside water pitchers that you can pick up and pour.
These filters work by allowing water to run through a substance called carbon. Carbon is a very common material that’s sometimes also called charcoal. Carbon or charcoal is created when plant materials are burned. That means you could theoretically make charcoal yourself! All you’d need to do is burn some wood at a very high temperature inside a sealed box.
The type of charcoal found inside carbon filters is usually made from burned coconut shells and is very pure. It’s also ground into a very fine powder, which increases its surface area. That means more opportunities for the charcoal to come into contact with the water you want to filter.
When water passes through the filter and comes into contact with the charcoal, anything dissolved in the water that’s made out of carbon has a chance to bind with charcoal in the filter. This binding process is called adsorption.
What can a carbon filter remove from water?
Loads of things are made from carbon and can therefore be adsorbed with a carbon filter. These include leaves, dirt, and chemicals produced by farms, factories, and cleaning products.
What can’t a carbon filter remove from water?
Anything that isn’t made from carbon won’t be filtered by a carbon filter. So you can’t use this kind of filter to remove most viruses and microorganisms, which are more common in well water. For these contaminants, check out Clean Cool Water’s list of best whole house water filters for well water.
This makes carbon filters best for improving the taste and smell of water rather than making water safe to drink.
2. Reverse osmosis (RO) filters
Reverse osmosis, also often called RO, is another common form of filtering found in people’s homes.
Reverse osmosis filters work by using pressure to push water through tiny holes called pores that are so small, almost nothing can fit through apart from the water itself. In good RO filters, the pores are so small that they’re measured in microns. One micron is equal to 0.001 millimeters, which is the equivalent of 1/1000000th of a meter!
This process is actually the opposite of how particles dissolved in water move in nature. Normally, water will also travel into places where there are more things to dissolve. This process is called osmosis. You can see osmosis happening when you go swimming or take a bath and your fingers get pruned. This is when your skin absorbs water and gets expanded.
Reverse osmosis filters are made to do the opposite of this process, which is why they’re called reverse osmosis. Instead of allowing the particle in the water to mix, they use pressure to force the dirty water to pass through the filter.
What can a reverse osmosis filter remove from water?
A reverse osmosis filter can remove almost anything that’s bigger than the pores in the filter. Normally this means things like bacteria, viruses, metals, and some chemicals like pesticides.
What can’t a reverse osmosis filter remove from water?
RO filters can’t filter out any compound with molecules smaller than water itself. This means some things that can be dissolved into water, including chemicals that are used by farmers to help grow crops.
3. Ultraviolet (UV) filters
Ultraviolet water filters, also called UV filters, are a little different than most other types of water filters. While you can still find UV filters in people’s homes, they won’t be in the kitchen. Instead, they’ll be attached to the place where water enters the house.
Ultraviolet light is a type of light that’s not visible to the human eye. Even though we can’t see it, we’re exposed to UV light every day from the sun. It’s actually a little dangerous, as UV light rays can damage or kill cells. That’s why it’s important to wear sunscreen on sunny days, which helps block out UV light from the skin.
Because it can kill cells, ultraviolet light is useful in water filtering. UV filters shine UV rays onto the water as it passes through the filter, killing small bacteria and microorganisms, and making viruses inactive.
While this isn’t filtering in the same sense as other types of filters, UV filters are great for turning unsafe water into a safe liquid to drink.
What can an ultraviolet filter remove from water?
Because they simply use a special kind of light, UV filters don’t remove anything from the water! Instead, they kill dangerous bacteria and viruses.
What can’t an ultraviolet filter remove from water?
UV filters can’t remove anything that needs to be traditionally filtered. That means things like dirt, chemicals, minerals, and metals.