Aluminum makes up about 8% of the Earth’s crust, making it the most abundant metal on Earth. It can also be found in water sources, particularly groundwater. While it’s not harmful to us in small amounts, excessive exposure to aluminum has been linked to several health issues, and ideally should be filtered from our drinking water.
Water filtration methods, such as anion exchange and reverse osmosis, are effective at removing aluminum from water. Anion exchange filters can remove up to 99% of aluminum, while reverse osmosis filters can remove up to 97%. However, carbon filters are not as effective and can only remove around 30%. The effectiveness of water filters is also influenced by how acidic the water is.
In this article, we explain how aluminum enters our water and how certain types of water filters can remove it. We breakdown the water filters that can remove aluminum into method e.g., ion exchange, and also by type, like pitchers, under-sink filters and bottles etc.
Aluminum In Our Water Supply
Aluminum is a light metal with a silver color. It’s the most abundant metal in the Earth’s crust, but unlike a lot of other metals, aluminum doesn’t have any significant health benefits to humans.
On the contrary, aluminum has been found to be toxic to the body. It affects some important metabolic processes and may also cause damage to some of our cells.
While there is no shortage of aluminum on the earth, this metal is rarely found in nature in its pure form. It usually combines with other substances to form compounds like alum and aluminum oxide.
Aluminum oxide is present in large quantities in a rock called bauxite.
Bauxite is the major source of the world’s aluminum used to manufacture several items, ranging from food packaging materials to aircraft parts.
Aluminum can get into our water supply from four main pathways:
1. Natural Sources
Because aluminum is present in large quantities in nature, when rain falls the rainwater dissolves aluminum in soils and rocks.
This water containing dissolved aluminum then seeps and mixes into underground water stores.
2. Leaching from Industrial Processes
A lot of industrial processes use aluminum. These processes range from mining to manufacturing everyday items such as pharmaceuticals, vehicles, construction materials, electronics, etc.
The waste products of these processes may contain high levels of aluminum that can run off into surface and underground water bodies, including rivers and lakes.
3. Water Treatment
Aluminum salts are usually added to drinking water during treatment to act as coagulants. Coagulants are substances that bind smaller particles together, forming larger particles.
These larger particles can then be allowed to settle and be filtered out.
Coagulation with aluminum salts should leave very little residual aluminum behind.
However, if the coagulation process is performed improperly, it may leave behind more aluminum than is necessary.
4. Leeching from the distribution system
Aluminum can rarely enter our water from components of the distribution system.
Cement pipes and pipe linings in water distribution systems may introduce aluminum in very tiny amounts from leeching.
Water Quality Standards
There are no fixed regulations by the United States government to guide the amount of aluminum that can be present in municipal or bottled water.
The United States Environmental Protection Agency, EPA, has National Primary Drinking Water Regulations (NPDWRs) that set mandatory standards known as Maximum Contaminant Levels (MCLs).
MCLs dictate the highest level of specific contaminants that are allowed in water.
These standards protect people against health issues that these contaminants may cause.
There is no specific MCL for aluminum. However, the EPA set an operational guidance (OG) value of about 0.05-0.2 mg/L.
This value is set with aesthetic considerations – such as taste, odor, and color – in mind.
They are nonmandatory and unenforceable, but public water systems generally follow these guidelines.
Apart from being aesthetically pleasing, water with an aluminum content less than the OG value is also considered safe to drink.
How Water Filters Remove Aluminum
Water filters can remove aluminum through ion exchange, reverse osmosis, and distillation.
Each of these methods has its pros and cons. Ultimately, the best option for you is determined by the quality of your water and other water purification goals you may have.
1. Ion Exchange
Ion exchange is a popular water treatment method, especially for softening hard water.
This filtration mechanism uses a special material known as an ion exchange resin, which is specially manufactured.
It’s important to know that there are 2 types of ion exchange – cation exchange and anion exchange – only anion exchange can remove aluminum from water (not cation exchange)
As water passes through the filter, the ion exchange resin binds certain anions, aluminum in this case, and replaces it with another anion.
Usually, the ion exchange resin needs occasional regeneration.
The regeneration process involves washing off the metal impurities from the water and flushing the resin with a solution.
The regeneration process is usually automated.
Unfortunately, salt regeneration cannot easily remove accumulated aluminum from the resin. Acid treatment is the best method for regenerating the resin.
While ion exchange is an effective way of removing aluminum from water, it is not well-suited for residential use because of the acid regeneration process. Except when used in water filter pitchers and under-sink filters, as it has been combined with the disposable filter that you simple replace, rather than regenerating.
2. Reverse Osmosis
Reverse osmosis is a popular method for removing aluminum from water because of its effectiveness.
It is great for residential use and can remove up to 98% of aluminum from drinking water. Reverse osmosis filtration systems also remove a wide range of other contaminants from water.
So if aluminum isn’t the only water contaminant you’re trying to deal with, then you should consider a reverse osmosis filtration system.
Reverse osmosis filtration systems use a high-pressure pump to force water molecules through a semi-permeable membrane. The membrane, often called the reverse osmosis membrane, has extremely tiny pores.
These pores allow water molecules to pass through but hold other contaminants back.
There are often also sediment filters that are used as pre-filters. They remove larger particles – like debris, dirt, and stones – before the water reaches the RO membrane.
Sediment filters protect the RO membrane from being damaged by these relatively large particles.
Depending on the manufacturer, a reverse osmosis filtration system may have several pre-filters and post-filters. This contributes to the effectiveness of RO systems in water purification.
The drawback of reverse osmosis systems is that they demineralize water. Reverse osmosis doesn’t remove just the harmful substances but may also get rid of the beneficial minerals in water.
A solution to demineralization is to purchase a system with a remineralization cartridge in addition to the filtration cartridge.
The remineralization cartridge will go a long way in re-introducing the necessary minerals removed during the purification process.
Also read about how you can add minerals back into your water here.
3. Distillation
Water distillation is a process that purifies water by boiling it until it turns into steam. When this happens, the contaminants present are left behind.
The steam then enters a condensing chamber where cooling occurs. Cooling converts the steam back into liquid. The liquid formed is pure water, free from contaminants.
Distillation effectively removes aluminum and other metals from water. The distillation process also sterilizes water by killing microorganisms such as bacteria.
Water distillation has its share of disadvantages too. One major drawback of water distillation is that it removes oxygen and good minerals from water, making it taste flat.
Although water distillation is one of the oldest water purification methods, it isn’t commonly used in domestic water treatment.
4. Activated Carbon
Activated carbon filters are common in pitchers, bottles, under-sink filters and even as one of the filters in a reverse osmosis system.
A small amount of aluminum can be removed by activated carbon, but this is usually no more than 40%.
The longer the water stays in contact with the carbon, the more aluminum can be removed.
Unfortunately, it would take more than 6 hours before just 60% of the aluminum is removed, and most activated carbon filters are gravity fed, meaning the water drips through the filter in a matter of seconds to minutes – not hours.
So, activated carbon is not ideal for aluminum removal, but is great as an additional filter when used in combination with anion exchange or reverse osmosis systems.
Best Water Filters That Remove Aluminum
There are several different types of water filtration systems that can remove aluminum from water.
Before buying a water filtration system, always confirm if it removes aluminum and any other contaminants you may be bothered about.
Some companies have the details of the contaminants that their devices remove accessible from their website. Reading these is a great way to get the information you need.
You can also contact the manufacturer and ask for specific details before purchasing.
Below is a list of some water filtration devices and information on how each can (or cannot) remove aluminum from water.
Water Filter Pitchers
Lots of water filter pitchers can remove aluminum from water. Most do so using ion exchange resin which is usually a part of a multi-stage filtration system in the filter pitcher.
For example, Clearly Filtered pitchers remove >88% aluminum and the Epic Water Nano pitcher removes 99.5% aluminum from water.
Also read about various water filter pitchers that can remove heavy metals here.
Water Filter Bottles
Water filter bottles that remove aluminum are not so common. In fact, we couldn’t find a single one that has test results showing it can remove aluminum. Hopefully, there will be one soon.
A water bottle filters would need to use ion exchange resins in addition to other filtration media to remove it, and most bottle filters only use carbon.
Under-Sink Filters
Most under-sink filtration systems currently available can remove aluminum from water, using ion exchange resins.
Under-sink filtration systems work to remove water contaminants just before it flows out through your faucet. Not all undersink manufacturers specifically list how much aluminum they remove, but Clearly Filtered state theirs removes 95.2% aluminum – not bad!
Faucet Filters
Faucet filters are effective and easy to install and can remove several common contaminants from water but cannot remove aluminum.
Water Coolers
Water coolers do much more than dispense cold (or hot) water. Some have advanced water filtration technology; however, we could not find any that remove aluminum.
Shower filters
Shower filters do not remove aluminum or other metals from water.
The design of shower filters is centered around removing chlorine and chloramines from water.
They carry out this function using filtration technology such as activated carbon, sand filtration, and redox (oxidation/reduction).
Water distillers
Though not very common, some countertop water filtration devices are water distillers. These water distillers, remove aluminum from water effectively.
Health Effects of Aluminum in Water
Aluminum is found in small concentrations in the water we drink and in the food we eat. At these quantities, aluminum is considered non-toxic.
However, when the aluminum concentration in water increases to unusually high levels, it becomes a health risk.
But even at such high levels, aluminum has been known to cause only relatively mild symptoms such as nausea, vomiting, diarrhea, skin ulcers, mouth ulcers, and in some cases, arthritic pain.
These symptoms are not only mild but are also short-lived. Aluminum hasn’t been found to cause serious or long-term health effects when consumed in drinking water.
When it does occur, aluminum toxicity is far more likely due to breathing it in as aluminum dust (which can be produced during industrial processes) or by ingesting it (e.g., in overuse of aluminum-containing medications such as some antacids).
One factor that explains the absence of long-term health effects of exposure to aluminum is that aluminum does not bioaccumulate (build up in our body).
It doesn’t bioaccumulate because our kidneys process and remove any aluminum that gets into our body.
This rapid excretion means that aluminum will not get the chance to build up and become harmful to organs in the body.
Some studies have loosely linked exposure to high levels of aluminum to neurodegenerative diseases such as Alzheimer’s and dementia.
But there hasn’t been sufficient scientific proof to back up these claims.
The precise effect of aluminum on the body is still not fully understood. So far, there is no specific answer to how much aluminum is safe in drinking water. `