Do Water Filters Remove E. Coli? The Real Answer Explained

We all know filtering water is important, but here’s a question that doesn’t get a simple answer: do water filters remove E. coli? Most of us assume our filters handle everything, but that’s not always the case.

A good water filter can make your water taste, smell, and look better. It can even deactivate harmful organisms. If you want the basics first, our guide on what filtered water is covers that well.

But E. coli is a tricky one. It’s a common bacteria that’s usually harmless, yet certain strains can cause serious health problems. With so many filter types on the market, let’s start by understanding how filtration actually works and which filters can handle this particular threat. Our guide on water filter cartridge types breaks down each category.

How Do Water Filters Work?

Water filters usually offer a physical or chemical barrier to contaminant particles present in the water. There are many different methods to achieve that.

Some methods are as simple as a DIY project you can do at home, or if you enjoy being outdoors, you could use these DIY methods while hiking or camping. Some other methods are more complex, and after years of development, many companies have come up with more effective and advanced technology.

It’s important to know that no single filtering method can guarantee 100% purity of your water. Different kinds of particles haven’t only different sizes but also other characteristics, which make them react differently to different processes.

For example, sand particles are 0.8 to 1.25 millimeters in diameter. Bacteria are between 1 to 2 micrometers long, which is almost 1,000 times smaller than sand particles.

To clean the water from both bacteria and sand particles, filters have to be fine enough to trap both these molecules. A sediment water filter handles the larger particles while other filter stages address bacteria. But that would mean a lot of problems with clogging the pores of the filter and with bacteria accumulation.

One of the main concerns households have with pathogens in the water regards a group of bacteria called E. coli. It’s very common everywhere, and in fact, you most probably have many of them in your body doing just fine, but it could potentially bring diseases.

What Is E. coli?

E. coli stands for Escherichia coli and it’s one of the most common groups of bacteria present in foods, water, the environment, animals, and humans. It’s often found in the intestines of humans and animals to help with gut regulation.

Rainfalls, hurricanes, strong winds, and other precipitation events can cause the bacteria to end up in rivers, lakes, and other water sources. When large quantities are consistently found in the same water supply, it could indicate sewage or animal waste being disposed of near or inside that water source.

Most E. coli strains are harmless to humans. But there are rare types that release a toxin and cause diseases that affect the blood and other parts of the body.

E. coli contamination can cause bloody stools, severe anemia, traveler’s diarrhea, and even kidney failure in extreme cases. These health consequences make it critical to make sure your water is free from this particular bacteria.

Most cities make use of disinfectants like chlorine to eliminate E. coli and other bacteria at their water treatment plants. A chlorine water filter removes residual chlorine from your tap water once it reaches your home. But it’s a long way from the water plant to your house, and your water could be recontaminated through the pipes along the way.

Although in most developed countries it’s very safe to drink water from the tap, you can find purifying methods that fit your budget and give yourself and your loved ones extra protection. For a dedicated solution, check out our E. coli water filter guide.

How to Detect E. coli in Water?

The bad news is that E. coli has no taste or smell, so you probably wouldn’t be able to detect it by yourself. You would need to send a water sample to a laboratory, and results would come back in a few days.

Faster tests are being developed, though. Some of them work like the universal indicator strips you may remember from measuring the pH of different solutions back in your high school chemistry class.

These tests would make it possible for you to know if your water is contaminated in a few minutes just by observing the color change of the special paper.

But unfortunately, these rapid tests haven’t made it to market just yet. The good news is that it’s not very hard to eliminate E. coli from water.

How Do You Eliminate E. coli From Water?

One of the safest and simplest methods is to boil your water. Boiling not only kills bacteria but also viruses and other living pathogens that might be present.

The one thing boiling doesn’t do is remove or neutralize some chemicals from the water. So many households prefer to have water filters that handle both.

Filters come in many styles and sizes. Some water filters can even be installed directly on your tap so you don’t have to refill a pitcher now and then, making them very convenient for daily use.

Here are some kinds of filters and other water purification products you can buy and use at home to protect against E. coli.

Ultraviolet Water Purifiers

These purifiers use a special lamp that emits UV light to deactivate living organisms like bacteria and viruses. The purifier is a cylinder that you attach to your main water supply pipes.

Inside the cylinder, a UV lamp emits radiation especially targeting microbes. This radiation uses a wavelength of light too short for your eyes to see, but it destroys the DNA of microorganisms and stops them from reproducing.

Even though we say radiation, you don’t need to worry about making your water radioactive. Ultraviolet is a type of light that has enough energy to destroy living organisms, which is why you should always remember to wear your sunscreen.

But it doesn’t leave any particle of radiation lingering in the water afterward.

The UV lamp needs electricity to work, so the purifier will be inactive for as long as you run out of power. This is an important consideration for areas with frequent power outages.

Can UV Filters Eliminate E. coli?

Yes, it’s an extremely effective method for eliminating E. coli and other pathogens in water. While effective at killing microbes, UV can’t substitute for physical filtering.

UV doesn’t affect non-living particles or chemicals. It also doesn’t remove or add odors or bad taste to water.

Therefore it’s very safe to use, as long as you don’t get in direct contact with the UV light inside the purifier.

But to improve taste and remove chemical impurities, you would have to use it in association with a water filtering system. In the end, UV could be a good substitute for using chlorine as water treatment, as it doesn’t present any danger for human consumption.

Portable UV Light Purifier

You could also get a portable option that wouldn’t require any installation or electricity from the wall to run. The portable option is just like a common flashlight, working like a miniature version of the bigger cylinder you would install at your home.

The small size makes it perfect for you to bring it with you in your purse or your backpack. To purify your water, you just have to place it inside your water glass or bottle, turn it on, and wait for the recommended amount of time.

It usually takes less than one minute and then you’ve water ready to drink.

It’s simple as that and perfect to take with you on a trip to a city where you don’t know if it’s safe to drink from the tap. It’s also a favorite among people who enjoy the outdoors, such as campers and hikers who need reliable water purification on the trail. The Sawyer Mini water filter is another popular portable option.

Reverse Osmosis

Reverse osmosis filters use the natural pressure of your water supply to push water through a semi-permeable membrane. It removes contaminants by only letting water particles through because they’re smaller than contaminant particles.

This system can filter chemicals, sediments, bacteria, and viruses. It has 3, 4, or 5 stages of filtration, with the standard models having at least three basic stages. Learn more about countertop reverse osmosis water filters for a compact option.

The first stage is a sediment filter, removing solids from the water. The second stage is a carbon filter, which removes chemicals like chlorine and herbicides.

The third stage is the membrane, filtering out larger molecules like viruses and bacteria, removing up to 98% of dissolved solids.

If your water comes from a private well, you’ve the option to add other personalized components to your filtering system depending on the exact composition of your well water. It will all depend on your needs. For those on well water, see our guide on how to install a whole house water filter on a well.

This system can change the color and odor of your water. It removes salts, sand, chlorine, herbicides, heavy metals, and many other contaminants.

This often improves the flavor of your water, although some people do prefer the taste of water with some minerals in it.

Maintaining Your Reverse Osmosis System

You’ve to be careful and keep your system always well maintained. If the membrane isn’t properly working, it can cause bacteria to deposit on it, which would contaminate your water.

You’ll know when the membrane isn’t working properly because your system will slowly decrease in the production of water. As soon as you notice any changes in the quantity of water coming out of your tap, you should have your system checked.

With good maintenance, your system could last you from 10 to 15 years. To keep it well maintained, replace your filters every 6 months to 1 year per the manufacturer’s recommendation.

Drain your Reverse Osmosis tank every 2 weeks, and sanitize your tank every year using specially designed products you can buy for this purpose.

If you need any help or if you notice any change in the water production, you can always schedule a maintenance visit with your filter’s provider or contact your local water treatment professional.

Activated Carbon Filter (ACF)

The Activated Carbon Filter is made of a special kind of powdered carbon designed to have a very large surface area that absorbs the contaminants in the water. By using chemical absorption, it traps contaminant molecules in between and inside of its molecular structure.

It’s specialized to clean water from pesticides, herbicides, and other chemicals. It’s very helpful in eliminating the bad odor and taste from water. For more on this technology, see our carbon block water filter guide.

Carbon filters can be made from different types of materials. The most common are wood-based media and coconut shell media.

Wood-based media is based on finely ground and burned wood. This media was used in Ancient Egypt nearly 6,000 years ago for water treatment.

The coconut shell media is the most eco-friendly option available today. Because it uses the coconut’s harder exterior, it doesn’t cause any allergic reactions or leave any sort of odor behind in the water.

Can Activated Carbon Filters Eliminate E. coli?

By itself, unfortunately no. Because of its molecular structure, pockets of stationary water can form inside the filter.

These pockets would then become the perfect environment for bacteria to grow and reproduce.

It’s important to notice that this applies to the vast majority of the activated carbon filters. Although some filters are certified to eliminate coliforms like E. coli, most can’t do so reliably.

Some companies also allow you to attach components to your filter, such as ones containing specially designed nano silver material which helps to kill microbes on contact. As for bacteria, Activated Carbon isn’t as safe of a method as UV light, for example. Read about the dangers of not changing your refrigerator water filter to understand how bacteria builds up in old carbon filters.

Ceramic Filters

Ceramic filters are one of the oldest water filtering methods available. They use small pores on ceramic surfaces to trap sediment and bacteria out of the water. The ProOne water filter is an excellent example of modern ceramic filtration.

Its two main parts are the upper part where the water is filtered and the bottom part, which is used to collect the drinkable water. It has a 0.5-micron filtration pore size, it’s inexpensive, and it’s very easy to maintain.

For this reason, ceramic filters are ideal to be used in developing countries where access to advanced filtration technology is limited. There are a few kinds of these filters available on the market.

Types of Ceramic Filters

Pot-type: Water is poured into the ceramic pot from the top and passes through the pores, collecting clean water in the container below.

Candle-type: In this model, a “candle” is added to it. Although they kind of look similar, it’s not like a traditional candle.

These are made of clay and placed inside the top part of the filter. Gravity water filters commonly use this candle-type design. Whereas in the pot type the water is filtered by the bottom of the upper container, in a candle-type the water flows and is filtered through the sides of the candle placed in the upper container.

This candle can have activated carbon to boost the purification process, and it can also have colloidal silver added to stop bacteria from growing.

Portable type: These attach directly to a water bottle opening for immediate filtration. Some are integrated into straws so you can drink directly from any water source.

Maintaining Ceramic Filters

Clean your filter regularly using water and a plastic brush or cloth. Never use metallic brushes or scrubbers since they could damage the ceramic pores.

If the filter hasn’t been used for two days, dispose of the old water and refill it with fresh water. Be careful when cleaning the candles as they’re made of very delicate material and can easily break.

If a candle falls and doesn’t visibly break, you can do a simple test to check for invisible damage. Simply put the candle underwater and place your finger over the outlet.

If bubbles appear, you should replace the damaged candle immediately.

Water Distillers

A water distiller boils water, captures the steam, and condenses it into cleaner, safer water. This is one of many approaches covered in our water filter cartridge types overview. The boiling process eliminates all bacteria and viruses.

Water first goes into a boiler with a heating element. Once the temperature rises, it kills all microbes.

The steam proceeds to a condenser attached to a carbon filter and transforms back into water.

Disadvantages of Water Distillers

Firstly, although it’s just about the purest water you could get from home, the whole process is quite slow. For countertop distillers that you would get for your kitchen, the purification can take from 4 to 6 hours to produce a gallon of water.

Another disadvantage of countertop distillers is that they have a small water reserve. It requires you to manually replenish the water every time a batch is finished.

This doesn’t apply to industrial-sized distillers, which can produce up to 12 gallons per machine in its reservoir.

Larger distillers with larger reservoirs are also usually automated to constantly work and replenish the water reserve by themselves. Due to its purity, distilled water can make drinking water very dull.

It’s tasteless to most people, and if you don’t like drinking water, this might not be the best method for you.

Another major disadvantage of this method is the amount of energy needed to process each liter coming out. The heating element requires a lot of electric power, which might affect your electric bill at the end of the month.

How to Remove E. coli If You Don’t Have a Filter

If you find yourself in an emergency without a filter, there are options available. A survival water filter is worth keeping on hand for emergencies.

Boiling

Boiling is the easiest and safest way to clean any harmful contaminants and make water safe for consumption. For this, you would have to make sure have a lighter or any other device to light up a fire.

Purification Tablets

Purification tablets are inexpensive and although they don’t leave a good taste in the water, they manage to make it safe for consumption. Make sure you’ve a few if you’re going to the wilderness or to a city where you’re not sure about the safety of the tap water.

They’re compact, lightweight, and easy to pack in any travel bag. Follow the instructions on the package for proper dosage and wait time before drinking.

Rainwater

If you don’t have any of these options available, try to collect and drink rainwater. It’s the safest natural option and it would be almost impossible to find E. coli in freshly collected rainwater.

Use a clean container to collect the rain and try to avoid letting it run off roofs or other surfaces that might introduce contaminants.