How is distilled water different from filtered water?
The goal of both 'filtering' and 'distilling water' is to produce water with fewer impurities. The main difference between distilled water and filtered water is that there is an active process involved in producing distilled water, whereas with filtered water, as it name suggests, water simply goes through a non mechanical filtering process only.
With distilled water, water is first filtered and then fed into a stainless steel boiling vessel. The water is heated to its boiling point until steam begins to rise and then channeled into a separate container where it will revert back to its pure liquid form without the impurities. With the rise of the steam, the heavier elements and impurities in the water cannot become part of the flow of steam and remain in the boiling vessel.
The purpose of distilling water is to create water that is free of nearly all of its dissolved impurities, and will contain only molecules of water.
Water can be filtered to all levels. Depending on the application the levels of filtration can be very low or can be surprisingly high. For example, in agriculture, water can even have been recycled from sewage and applied to certain agricultural products such as citrus fruits which are thick-skinned. Municipal and domestic gardens are another place where you will find some forms of recycled filtered water being used to irrigate. Recycled water needs to go through several stages of filtration before it can be used. Recycled water will generally have its own piping system to totally reduce the possibility of it being drunk.
Other techniques of water purification exist that are even better than filtering, such as Reverse Osmosis and Deionisation, however, Distilled Water is still regarded as the preferred method of producing ultra pure water with a very low conductivity as it can achieve much greater purity than any of these methods.