Filters

OK, so you understand now why you have to purify your water (or if not, click here). BUT there’s a bewildering array of claims out there regarding different technologies, and their effect on the water you drink and work with.

Let’s start to make sense of them, by running through what the technologies are and what are their pros and cons.

1. Granular Activated Carbon (GAC) filters – possibly the most widely encountered filter type, found in jugs, shower heads, gravity-type countertop filters and others. Powdered charcoal is treated with oxygen to open up millions of tiny pores between the carbon atoms. When certain chemicals pass along the carbon filter, they are attracted chemically to it and are trapped. The chemicals that are attracted are other carbon-based impurities, sometimes called “organics”, particularly those chemicals created by the oil industry, and chlorine. Other chemicals, such as heavy metals, asbestos and nitrates, pass straight through without being attracted. The higher the quality materials used, the greater the surface area of filter, and the greater the quantity of bonding sites. The cheaper the materials, the faster the filter becomes clogged, and the quicker you need to replace the filter. Most jug filter companies, for example, publicise that the filters need replacing at least every 40 gallons.

2. Ceramic filters – typically made of material similar to bone china. The small pores in ceramic filter out larger contaminants such as bacteria. Generally these are used in a gravity-fed device, with the trapped contaminants remaining at the top – and either requiring regular cleaning out (eg with soap and water), or the whole filter has been treated with silver, an effective bactericide. Ceramic filters tend to filter out pathogens only, and so more often are used in combination with other filters such as GAC filters.

3. Distillation – water is boiled, and the resulting steam is passed onto a condenser that cools the steam back to a liquid. If gasses are vented properly, this can be a reasonably effective method of “removing” contaminants from water – although it might be more accurate to say that it’s removing the water from the contaminants. Heating the water tends to kill most of the micro-organisms. This method tends to be only average in capturing pollutants like “organics”, such as pesticides, and also asbestos filaments tend to go with the steam. The other problem with this type of filter is it tends to be highly inefficient, only producing a small amount of water from a large source.

4. Ultraviolet – just as with distillation, this is not a filtering process. Exposing water to ultravoilet light is similar in effect to heating it. In this case, if you find the exact right wavelength, it can be highly effective in killing fecal coliforms, viruses and other pathogens. It doesn’t tend to kill cysts like giardia, and it doesn’t filter out any minerals or pollutants, so normally needs to be paired with at least one other technology.

5. Water treatment – water companies treat water in a number of ways, depending on the make-up of the source water. In BC, the water may be treated to UV, but in particular will be chlorinated. This is because the primary health risk in water supply is seen as from diseases such as typhoid, and chlorine is highly effective in killing bacteria, pathogens and fecal coliforms. In the US water treatment can be via compounds of chlorine such as chloramine, as otherwise chlorine can readily form by-products like chloroform that have potentially cancerous effects. Fluoride is also used, but again health concerns abound. In Europe water tends to be treated with ozone, but again there are health concerns. You can read more about health concerns relating to chlorine and chlorine by-products here.

6. Reverse osmosis – water is pushed under pressure through a selective (“semi-permeable”) membrane, typically removing most organics and inorganics, but often not the smallest pathogens, iron, and a handful of other pollutants.

7. De-ionisation – is an electrical process that swaps out for example magnesium, calcium and sodium molecules for hydrogen. This is a key part of Aquathin’s patented process, removing the last impurities that are not removed by either the GAC initial process or more likely the Reverse Osmosis.

To understand how Aquathin combines these processes in a patented sequence, click here.