Water Filters: The breakdown

Which water filter should you get? In the 21st century, there are many many types, from ionisers to distillers to carbon filters. Each claim to be the fountain of youth. In this post, I’ll break down what each of these remove. As a side note, I’ll be discussing under the sink options mainly and not the survivalist bottles.

Carbon block filters - these are your first level as it were of water filtration. The carbon substrate in them has a large surface area in which the water is forced through. This reduces chlorine, organic compounds and certain VOCs but it does not remove things like fluoride, nitrites, lead, acids (e.g sulfuric), pharmaceuticals and microbes. Total dissolved solids (TDS) = High.

Water ionizers - these work by the process of electrolysis (water runs over positive and negative electrodes). These remove acids and the carbon block in them reduces chlorine, organic compounds and certain VOC’s but suffers like the carbon block filter in terms of what it doesn’t do. TDS = Medium to low.

Water distillers - A slow process, converts water into vapor before condensing it and returning it to a liquid state. During the evaporation process, impurities like bacteria, heavy metals, and arsenic are eliminated because they are unable to turn into steam. Not designed to remove chlorine and other chemicals completely from water. Organics such as herbicides and pesticides cannot be removed efficiently. TDS = Low.

Reverse osmosis filters - removes contaminants from water by using pressure to force water molecules through a semipermeable membrane (extremely small). Usually quite wasteful in terms of water out although this is improving. These remove most things (like distillers), including TDS, organics, pyrogens and bacteria but do not remove acids, chloramines and trivalent arsenic. TDS = Low.

When it comes to the last two which produce very low TDS, you have to be careful. When water drops below say 10 or 20 ppm, it becomes very unstable and will pull minerals out of your body. We want to retain some of these minerals, especially magnesium bicarb. The sweet spot I think is between 80 - 90ppm, the equivalent of high altitude spring water.