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Boiling and filtering are two common ways to purify water. But while they both do the same job of purifying water, the result is often completely different.
Here’s an in-depth look at the pros and cons of boiling water vs. filtering water. At the end of the discussion, we outline which of the two methods are better and why.
Boiled Water
Boiling water is the most well-known way to purify water and has been used for centuries. For people with limited access to clean water, especially in underdeveloped countries, boiling offers an easy and cheap way to make water safe to drink.
Effect of boiling on contaminants
Boiling your water removes a range of biological contaminants including:
- Viruses
- Bacteria
- Spores
These harmful microorganisms can’t survive in the intense high temperatures of boiling water and are inactivated.
On the plus side, boiling doesn’t remove the minerals in water, such as calcium and magnesium. These minerals are necessary for our body and are completely removed by other types of water purification, notably distillation.
However, by the same token, boiling water also doesn’t remove other type of chemicals such as chlorine or lead. By boiling water containing these chemicals, it will simply lead to concentrated levels of the chemical in the water. This can make it even more harmful than if the water wasn’t boiled.
How to boil water
Depending on the quality of the feed water, the best practice for boiling water as outlined by the CDC differs.
If the water is cloudy:
- Filter the water through a clean cloth, paper towel or coffee filter. If you don’t have access to these items, simply let the water sit in the container and allow it to settle.
- Pour the clear water into a pot or pan.
- Allow the water to come to a rolling boil for 1 minute.
- Let the water cool before using.
- If storing, use a clean container with sanitized covers or lids.
If the water is clear:
- Boil the water at a rolling boil for 1 minute.
- Let the water cool before using.
- If storing, use a clean container with sanitized covers or lids.
Note that if the water looks dubious or comes from an untrusted source, increase the boiling time to at least 10 to 15 minutes.
While boiling purifies the water, note that it doesn’t filter, so you may find that any particles in your water will still be there.
If you’re at elevations above 6500 feet, boil the water for three minutes instead of one. This is because atmosphere pressure drops with increased elevation, which results in lower boiling temperatures of water.
Pros and cons of boiling water
Pros:
- Easy and convenient way to purify water
- Kills biological contaminants in your water
- Safe and sure method
- Requires minimal equipment
Cons:
- Particles and solids will not be removed
- Doesn’t remove chemicals
- Uses up energy
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Filtered Water
Filtering water is one of the most effective and widely used methods of purifying water. It’s a versatile method that has a variety of options to choose from. Filtration works by using chemical and physical methods to treat water, which removes almost all contaminants, resulting in clean and safe water.
What contaminants do filtration systems reduce?
By filtering water, you can target all types of contaminants that are commonly found in water. This includes biological, chemical, radiological and physical contaminants.
Different filters are designed to remove certain impurities, but some more complex and advanced filtration systems can effectively remove or reduce all types of impurities.
The following are some of the contaminants that a filter can remove:
- Heavy metals like nickel, arsenic, lead and mercury
- Pathogens like viruses, microbes and bacteria
- Chemicals like chlorine and iodine
- Minerals like calcium and magnesium
- Pesticides, herbicides and pharmaceuticals
- Sediment which is common in groundwater which percolates through sedimentary rocks.
- Volatile Organic Chemicals (VOCs) are chemicals that vaporize into air or dissolve in water such as benzene or toluene
Ways to filter water
There’s a wide range of filter options out there which means that before selecting a filtration system, you will need to find out what exactly you want your system to do for you. Here are the most common ways to filter water:
- Reverse Osmosis Filters– One of the most popular and most effective filtration systems, reverse osmosis works by pushing water through a semi-permeable membrane under pressure. This takes the purified water to the other side, leaving the wastewater with contaminants on the other. The trouble with RO systems is that they can demineralize the water and also result in a significant amount of wastewater.
- Ion Exchange Filters – This is the most popular filtration option to soften water. It works by exchanging mineral ions that cause hardness with sodium ions that soften water. While this works to effectively filter out hard water, it doesn’t effectively filter out other types of pollutants. Ion exchange works best when combined with another filtration system.
- Activated Carbon Filters – These are the most commonly used and most inexpensive type of filters. They work by absorbing impurities resulting in water that is free of most contaminants, bad odor and taste. However, viruses and bacteria can get through this type of filter.
- Multi-Level Carbon Filter – One of the most economical types of filters, multi-level carbon filters work by pushing water through several layers of filters. Because there are several levels of a variety of mediums, the water leaves behind its contaminants as it gets pushed through the multiple layers. This is effective in removing most types of water borne contaminants, but multi-level carbon filters don’t always effectively remove chlorine.
- KDF Filters – KDF stands for Kinetic Degradation Fluxion which is a patented filter material known for its effectiveness in removing chemicals like chlorine from waters. It uses a special granular zinc alloy that creates an electrochemical reaction when it comes into contact with chemicals. During this reaction, electrons are exchanged between the molecules, resulting in new elements being produced. The structures of some harmful chemicals like chlorine are changed into harmless components while others, like copper and mercury are removed altogether from the water.
Pros and cons of filtering water
Pros:
- Sustainable solution with minimal water wasted and energy used
- Depending on filtration method, removes all types of contaminants
- Depending on type of filter, doesn’t take away essential minerals and trace elements
Cons:
- Can be expensive
- Difficult to install depending on type of filter
- Ongoing maintenance – replacement of cartridges
Boiled Water vs. Filtered Water – Which to Choose?
On analysing these two types of water purification methods, it’s clear that filtration is a more sustainable, effective and reliable method.
Firstly, from the two, filtering your water gets rid of more impurities than boiling alone. Boiling doesn’t remove harmful substances whereas a good filtration system can remove up to 99% of all contaminants in water.
Secondly, filtering is a lot more convenient than boiling water because it doesn’t require any effort. Once you’ve done the initial investment of time and cost, the filter will continue to provide you clean water at the turn of a faucet. While you will have to replace the filter cartridges periodically, this cost is made up for by the fact that the typical filter doesn’t require energy to make it work.
Thirdly, filtering offers you solutions for clean water throughout your home and not just out in your kitchen out of a kettle. While boiling is a good option for clean drinking water, filtering is much more effective if you want clean water in your whole home, including kitchen, bathrooms and laundry.
The Bottom Line
There are several key differences between boiling and filtering water, but the overall consensus is that filtering your water is a much more effective, sustainable and convenient way to purify your water.
Boiling does have its uses, especially when in emergencies where access to filters or clean water is limited. In such situations, boiling water can make it safe to consume. But as a long term solution, filtering is, without doubt, the better option.
