Lava Rock Filtration Explained

We've all heard or seen it before in marketing messaging for bottled water brands: lava rock or volcanic rock filtered water. But what does lava rock filtration mean and why should you care about it? All bottled water has to be purified and filtered, but that process strips out many of the naturally occurring minerals in drinking water that make it taste so good. The unique characteristics of volcanic rock, combined with heavy annual rainfall levels on volcanic islands create a natural water filtration process.

What is Lava Rock

Lava rock or volcanic rock is what liquid hot molten lava becomes when it cools and crystalizes. Volcanos spew out magma from the earth's core and deposit it along the slopes of a volcanic mountain. Technically, volcanic rock is a type of igneous rock called basalt, which can be found in abundance in certain part of the world, especially in the pacific volcanic islands. Basalt rock is just about everywhere on earth, and it is even present on the moon. On earth, it underlies all of the great underwater ocean basins, and it abundant in the ocean floors beneath volcanic islands. The porous nature of Basalt, along with other physical characteristics, makes it ideal for the natural filtration of water. This comes in very handy in Hawaii where there are a lot of volcanoes, rainfall and pristine artesian wells. Because certain islands have active volcanos, there is a constant replenishment of new rock, which add to the natural filter.

How Does Lava Rock Filter water

Imagine a sponge, with its rubbery feel, squishy consistency and its porous make-up. Water can pass through a sponge without much trouble. Now imagine that sponge is hard substance with a crusty out layer with porous skin that is made of hard, lightweight silica and other minerals. Water can still pass through it, but also pass over it. Now imagine that giant rock sponge was once in the form of liquid magma, and was formed by cooling and crystalizing. Lava rock is a common filtration media in aquariums and ponds, where the porous surface of the stones creates greater surface area where the biofilm can accumulate and act as a filter for bacteria. In nature, the force of constant rainfall in places like Hawaii utilize the rocky landscape from lava flows from active volcanos to push water through and over the porous rock. Sediment and bacteria collect in the biofilter on the rocks, and excess water flows and drains into artesian aquifers below. This natural filtration allows for certain minerals like magnesium and calcium stay in the water, which gives it a unique alkaline taste.

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What Are Total Dissolved Solids in Drinking Water?

We all need water to survive, and those of us lucky enough to live in the developed world have many choices when to comes to selecting how we get our drinking water. Some people spend extra money on purified water home delivery services, where the water is delivered in large 5 gallon jugs. Others chose to rely on municipal water supplies and get water straight from the tap, and then use home filtration to mechanically filter out impurities. Either way, we need to make sure the water we drink is from a good source and has been filtered, purified and sanitized for human consumption. So what exactly needs to be filtered out? It depends on the source.

Water coming from the ground well or ground aquifers will have what is referred to as total dissolved solids, or TDS. This refers to dirt, chemicals, bacteria, pathogens and other impurities that are small enough to pass through fine filter membranes and end up in the liquid. This is why it is called dissolved solids. TDS is measured on a part-per-million basis or PPM, and is a standard testing benchmark in water purity measurement. In the United States and Canada, a TDS reading of 500 (500 parts per million, which can also be expressed as 500 milligrams per liter) is the threshold for safe water.

TDS (parts per million)


0 to 300


300 to 600


600 to  900


900 to 1,200


Over 1,200



But dissolved solids can be both organic and inorganic, which creates another layer of detail required to evaluate the quality and safety of drinking water. Groundwater naturally contains higher levels of organic solids including inorganic salts like magnesium, calcium, potassium and sodium, which is generally safe at lower levels. In fact, premium alkaline bottled water, high in pH is generally considered to taste better because of these minerals. Dissolved organic solids, like mineral, can also create ‘hard water’ which can clog up appliances like washing machines, dishwashers, coffee machines and the like. Because hard water from the ground is prevalent in certain parts of the US, water softening services and devices are quite popular. Inorganic matter is a different story. Sulfate, iron, manganese, petroleum, pathogens, and other man-made contaminants create much more danger when to come to drinking water, and contribute to TDS.

Measuring the TDS in drinking water is essential to maintain safe drinking water supplies for the general public. When a water source has a high level of TDS, it is likely that there are some harmful contaminants in the water. TDS is also easy to measure and if something is happening to water, such as pollution, and chances are TDS levels will change, so keeping track of these changes can act as an early warning signal that something wrong is going on with the water. For these reasons, it is important to monitor the TDS levels in public water, so that if they change, action can be taken immediately. If you’re interest in measuring the TDS in your tap water home, you can buy an in inexpensive tool here. For more information about how TDS is measured and how we can all maintain safe water supplies, please visit the Safe Drinking Water Foundation website.

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How do Charcoal Water Filters Work?

Many home water filtration systems feature charcoal-based filters, but have you ever wondered exactly how charcoal is used in a filtration system to filter water? Charcoal is a great natural ingredient for water filters, but the charcoal actually used to filter is called activated charcoal, which is different from the charcoal you use in your backyard bbq. Activated charcoal is generally crush up into small pieces, which allows for more water to pass over the surface area of the charcoal, and expose more water molecules to the pores in the charcoal. Activated charcoal purifies through the process of adsorption (not to be confused with 'absorption'), which is where the charcoal chemically binds impurities in the water to the surface of the charcoal filter particles rather than physically absorbing them. Activated charcoal is an ideal water filter because it removes toxins from the water without stripping the water of salts and other important minerals. These adsorption qualities of activated charcoal is why you hear of people using it to try and clean out their system from toxins and impurities like alcohol, and use it as a hangover treatment. There is no real science that supports this idea.

So, for water filtration, there are three primary processes:

  1. Mechanical filtration – This is the process of forcing water, either through pressure or gravity, through a fine membrane to physically or mechanically remove particles and sediment from your water. Small debris like sand, dust, dirt and other sediments are the first foreign substances that need to be removed from water during the purification process. Some filters will emphasis the size of the holes in their filters and membrane by pointing the size of filtered out material in microns. Generally speaking, a 1 micron filter in quite fine and will remove most if not all particulate, as well as small bacterial particles called cysts like Giardia and Cryptosporidium.
  2. Carbon/charcoal filtration – Most water filter systems use the pores within carbon or charcoal to remove the unpleasant tastes and odors which can be caused by a variety of factors, including chlorine and other chemicals, old underground pipes and unstable levels in water tables and aquifers. This second layer or level of filtration ensures that your water looks and tastes as appealing as it can.
  3. Removal of some minerals, including limescale – Limescale and other minerals can accumulate and is not good for your water using appliances like your coffee maker or dishwasher.

Some of the benefits of charcoal-based filtration:

  1. The good stuff isn't filter out of your water, only the bad stuff that might be lingering in your pipes like copper, mercury and cadmium
  2. Your water will taste better. While important in disinfecting your water, chlorine has no value to your mouth and tongue.
  3. Very inexpensive compared to bottled water
  4. Easy maintenance – by replacing the filter every 12 months, you can help make sure the water you drink from you home system will taste as good as it can.

How is Drinking Water Filtered?

We don't always think about the water we drink. Somehow we just taking healthy hydration for granted, but we all know we shouldn't. It is one of the great flaws us human things have. It is difficult for us to see thing from a different perspective, which is why unless we are affected first hand, we just assume our drinking water is clean, healthy and free of contaminants impurities. But ask anyone living in India, Southeast  Asia, Latin America or any other place where drinking water isn't always the cleanest

As a child, my family's vacation home in Southern Vermont was a affected by a ruptured heating oil tank, which leaked oil which eventually leeched down into the water table. Because the house drew its water from a nearly well, the tap water began smelling like heating oil, and at one point the water coming from the tap was flammable. Ever since then I have wondered about how water gets into our homes, and how it gets filtered - either naturally or mechanically -  before humans consume it. For municipal water supplies, groundwater passes through layers or rock and sediment en route to an underground river or aquifer. From there, it is pumped out and fed into infrastructure where chlorine (to kill off any remaining bacteria) and Flouride (for oral health) is added. Other homes off the 'water grid' use wells to draw water from aquifers. But the process for bottled water is different. The drinking water you get in a bottle at the store generally come from one of two places; the tap or the ground. If it comes from a tap, it is 'purified' to remove any bacteria or pathogens before it is bottled. It can from underground aquifers, but it is same basic water municipalities take their water from. The second type of bottled water is spring water, and it bottled 'at the source', which means all of the naturally occurring pH and alkalinity from mineral remains mostly intact before it gets to your lips. This makes a big difference when ti comes to taste, and also when it comes to cost. Marketers and bottled water brand like to emphasize the naturally occurring levels of purity and pH in their water, and you can taste the difference in some brands. Lava rock, for example, is an excellent natural filter for artesian spring water, and because it require less purification, all of the naturally occurring minerals remain, which add to its character.

Water coming from high mountain springs taste great because it:

  • It pretty clean to start with and, depending on the mountain, doesn't require chemical purification. It usually starts as snow, and then melts in to water and then seeps into underground creeks and rivers before coming to earth's surface.
  • Is filtered naturally, and therefor is potable with the least amount of mechanical or man-made filtration and purification. This is 'bottled at the source' means higher quality.

Camping supply companies have come up with fancy filtration products for mountaineers who are trekking at high altitudes and can't carry a lot of water because of its weight. But the more distance the water travels, the more the need to chemical purification like iodine tablets. So, the water you drink is filtered either mechanically or chemically or both, depending on where you get it. If you are the outdoor type who likes to hike and camp and take water from the ground, it is always a good idea to carry both types of filtration tools and a water testing kit with you so you don't get sick.

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