Britta filter for drinking/coffee

ok im assuming im wrong on this but doesn’t activated carbon remove TDS? Britta’s water filter is basicly just carbon and for kicks i used my new TDS meter before and after and both come out around 120.

shouldn’t the filter remove any TDS, or does what it removes not affect dissolved solids?

Carbon does not remove TDS, it will remove chemicals, organics and other toxins which will contribute to the TDS and using carbon should lower your TDS reading depending on the contact time. I am not sure how large the chemical chlorine is but I would guess it is relatively small in the relation to the solids in the water. I would guess salts would be the largest % of the TDS #. Activated carbon is not a cure all but for select organics works very effectively. Also a simple floss filter will lower TDS.
Britta does not have a very long contact time so I would guess they are aiming at removing things that affect the taste or color of the water, chlorine being the most obvious. In RO/DI units it is used to remove select chemicals that can damage the DI resin.

Total Dissolved Solids (often abbreviated TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. Generally the operational definition is that the solids must be small enough to survive filtration through a sieve the size of two micrometer. Total dissolved solids are normally discussed only for freshwater systems, as salinity comprises some of the ions constituting the definition of TDS. The principal application of TDS is in the study of water quality for streams, rivers and lakes, although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects) it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants.

Keep in mind the importance, some people believe, of 0TDS water in Reef tanks. Even if you are getting 2-3ppm TDS from your RO that could be phosphates or silicates or exactly the stuff you do not one. Often the worse stuff shows up first and hardly affects the reading of your TDS meter.

If the worse stuff that effects reef tanks gets through first and doesn’t affect TDS, perhaps it is the same for Brita filters and you cannot measure their effectiveness through simple TDS.