Let’s Talk Silver

Use of silver in water treatment

Silver Myth

Silver can kill bacteria. Right? Well, yes and no, let’s take a look.

There is an old belief that if a silver spoon is placed in a water pitcher, that water is now bacteria free and safe to drink. In reality, silver, in its metallic form is practically inert and does nothing except maybe having some placebo effect. On the other hand, silver is a heavy metal, classified as hazardous. Silver is more toxic than lead and is almost as toxic as mercury (per unit of mass) in its active form, i.e. ions of silver. And yes, in that form, it can kill bacteria, microorganisms and even body cells. Silver is considered contaminant and its allowed concentration in drinking water is regulated and limited in many countries. But then why is it allowed to be used in water treatment?

Silver Ions

Now let’s stop for a second and think about what is written in the previous paragraph. Silver ions are poison.¬†If you have any water filter or device that claims to enrich water with silver “for your health benefits” you have to immediately stop using it! This is not the same as “alkaline water” (that doesn’t do any good, but doesn’t hurt either), eating or drinking silver is actually dangerous.

But that brings us to the next point – use of silver in filters. As we learned before, if filter cartridge is impregnated with silver in its metallic form, then this is nothing more than marketing move. It practically does not do any good or bad.

Real Deal

Now what about the proper use of silver in water filtration?

Second options is often used in carbon cartridges. Small portion of carbon is soaked in silver salt and then mixed with the rest of the carbon. When using the filter, silver is slowly regenerated and particles get “stuck” inside carbon cartridge pores and, in theory, should not make it the drinking water. However, change in pressure and some other factors may result in release of these silver particles which will end up in your drinking water. In many EU countries, cartridges of this type are simply banned.

Final option (the one that is used in high quality filter cartridges, including Aquaphor, Disruptor stage 2 and 3) is to securely affix silver ions inside the cartridge so that they do get in contact with water and yet are not flushed down to the cup. Example of that would be Aqualen from Aquaphor – ion exchange fiber. Similar technology is used in other top quality cartridges.

Actual effect

It is important to understand that even when the silver is properly applied to the cartridge it does not make kill all the bacteria that enter the cartridge. It inhibits bacteria growth inside the cartridge, therefore allowing longer cartridge life. It does not replace UV/UF/Electroadhesion or other bacteria removal technologies. It also should be mentioned that some quality cartridges may not even mention silver inside. It is simply implied that if cartridge is guaranteed to last a year or so, there is silver there.

Conclusion

Just like most things in life, silver in filters is definitely good or bad. All depends on how it is applied. Metallic form of silver has nearly 0 effect, so you can take out silver spoons out of your pitcher. “Active silver enriched water” is big no-no, while active silver used to inhibit bacteria growth only definitely helps to prolong the life of the cartridge and its resistance to bacteria.