TDS

TDS or Total Dissolved Solids are measured in mg/L (milligrams per litre) or parts-per-million (PPM). According to the EPA, our drinking water should not contain more than 500ppm of TDS. Most of the private wells we've tested in our area contain 400ppm or much higher.

While testing for TDS does not tell you what is in your water, it is a very good indicator of just how bad off your drinking water may be. By the way, it should be mentioned that TDS readings under 200ppm should only require RO (reverse osmosis) treatment or even a POU (point of use) taste and odor filter for great tasting, safe water.

Some of the contaminants or dissolved solids that can increase your TDS readings are aluminum, arsenic, asbestos, cadmium, chlorine, chromium, copper, endrin, flouride, giardia/cryptosporidium, hardness, lead, mercury, nickel, nitrate, pesticides/herbicides, radium and radon. There is potential for many more contaminants, but the list would be beyond the scope of this article.

If you own an RO system, it would be a good idea to check the TDS output every 15 to 30 days. Keep an extra pre-filter around and change the old one out when your TDS levels increase. This is especially important if you own one of the more expensive ROs. Membrane prices can reach as high as $100 each and some ROs require two membranes. The cost of a TDS meter and an extra filter can save you a great deal of money down the road.

You can get pre-filters for all of the reverse osmosis systems we carry here, and an accurate, reliable TDS meter here.