Unless we’re on a warm beach, lying on a towel, and basking in the sun, we never think about sand; especially in the ways it can be used to filter our water for the better. While pink sand beaches may tantalize our dreams (and make us think about when we may book our next vacation), greensand is the culprit making water safer to consume for many communities. But what is it?

Greensand filtering is just as literal as you may expect. A type of sand sediment with a green consistency, texture and colour with the capability to filter out impurities. The key mineral of glauconite is what makes greensand so optimal for water filtration. Coated with manganese, greensand becomes the perfect filter for naturally-occurring minerals such as iron and hydrogen sulfide. While iron is considered a “secondary contaminant”, meaning it doesn’t pose a real threat to human health if consumed. The Penn State College of Agricultural Sciences reports that tap water, per litre, should have no more 0.3 milligram of iron. This means, for example, well water, that contains more than the recommended human intake, needs filtration in order to remain safe to drink. Greensand is a great option to do this -- but is it the best filtration option?


Where Did It Come From, and How Does It Work?

We can look to the use of greensand filtering as early as the 1900s, but it was abandoned by -- what one could argue -- higher-tech water filtration methods around the 1970s, and technically put out of use in the United States around the 1950s. Still, the natural workings remain impressive. Manganese greensand remains the right sizing to catch iron. This can be done without adding anything to it, so this means to remove iron, greensand doesn’t technically need any additional filter media or additives.


“Like the Sands of the Hourglass…”

There’s also something to note about the remote capabilities of certain sand filters for water treatment. While membrane filtration, such as nano or ultrafiltration, requires more energy consumption, certain gravity models of greensand filters require little to no electrical consumption. Perfect for cottages, camping grounds and areas where we might not inhabit the lot 365 days of the year, the tech promises to remove up to 99.99% of all bacteria and viruses. While the usual iron and manganese is removed, bacteria like  Giardia and Cryptosporidium also get cleared through the process. If slow and steady wins the race, then this could be a great option. With the filtering happening at the rate of 0.1 gallons, per minute (depending on the square footage), it’s a real toe-tapper, watching-checking technology, but the potential is there.


Sink or Swim

Most pool owners know that hard water can affect the functionality and enjoyability of their swimming pools. Also, too much sulfur in the water can lead to skin irritation. Given this, Scotland embraced greensand filtering in over 50 swimming pools in the country, ensuring the water remains clear and odourless. The best part: the filtering is done through recycling beverage glass to create the system. That’s right: as an effort to reduce and reuse, a factory in Bonnyrigg, Scotland holds the capacity to recycle a quarter of Scotland’s glass, and then convert it into greensand for swimming pool filtration in the country. But that’s not all...

Revolutionize Recycling

It isn’t just for swimming pools. While some water filtration like membrane filtration can require a lot of energy, greensand shows promise in its recycling potential beyond just the kiddie pool. In fact, the European Union invested £1 million in an attempt to open a plant that converts soda bottles back into sand for drinking water filtration.  If this sounds like recycling heaven, that’s because it is. Not only would the plant lead to wastewater treatment for drinking water in municipalities, but the additional second life of beverage bottles means less in the landfill, and water that can be enjoyed again.  The idea that glass beverage bottles are guaranteed to be contaminant-free due to its use for consumption make this the perfect idea on paper. The UK plans to open 6 plants, with initial testing before mass expansion.

Given many filtering plants using new, more rigid technology to filter drinking water, greensand filtering may not sweep the nation anytime soon with a roaring comeback. Despite the abandonment of greensand in the United States, the method of filtration still stands out as one that requires little maintenance or modification to be and stay effective. The new investment put towards greensand filtering in UK and Scotland suggests an environmental trend we may not be privy too yet -- or just wild experimentation that could go horribly awry. Still, with water crises across the U.S. states, it might be time for us to look to our neighbours across the pond, and see a little green to mimic their efforts. Greensand: a new wave of water filtration, or just another coloured sand in a bigger sea? It’s our time to see.

Published by Steffen Ploeger