EPA Standards Miss Many Chemicals in Drinking Water, Study SaysMore
RO water filters reduce the concentration of dissolved chemicals between 85 - 95%. Depending upon the how well your RO filter is performing, and the quality of incoming water the output TDS may be up to 95% less. With water that has TDS between 100 to 500 mg/liter, the purified TDS will range between 5 and 30 mg/Liter or ppm. Some people believe that this water may be harmful for health.
Some RO purifier manufacturers employ a TDS controller. It is a screw-based device that controls the level of “total salts” in the purified output water. It works by adding a percentage (adjustable) of source water bypassing RO membrane to the output water, which is then passed through a carbon filter, and/or UV tube.
The water going into the TDS controller is divided into 2 parts:
Part 1: This part goes into the RO membrane, resulting in pure water of lowest TDS possible.
Part 2: This water does not go through the RO membrane. It goes through an Ultra Filter membrane / or carbon filters, depending on the specification of the RO purifier. The UF membrane does not filter ANY of the dissolved solids including Ca, Mg, Na, heavy metal ions, arsenic, lead etc. The only two membranes which can do this is RO membrane and to a lesser extent Nano filter membranes. In essence the TDS controller is adding back all these harmful and other chemicals back into the purified water.
You decide. The very contaminants you want removed are being added back to the water you will drink, albeit in small quantity. People believe that by TDS controller essential minerals are retained. A water of 50 mg/liter of TDS may have up to 5 -10 mg of Calcium, a few mg of Magnesium and potassium, sodium. A typical male/female’s daily requirement of Ca is 1000 - 1200 mg. With 10 mg / liter of Ca, imagine how much % of RDA you will get by drinking 1 to 2 liters per day. Yes 2 % or less.
It may be better to get a RO water purifier with no TDS controller. They will offer the best protection against pollutants, pesticides, and heavy metals.
Milk, lentils, meat, vegetables, fruits and other food can provide the essential minerals.