Frequently askedquestions

The EPA Secondary Regulations advise a maximum contamination level (MCL) of 500mg/liter (500 parts per million (ppm)) for TDS. Numerous water supplies exceed this level. When TDS levels exceed 1000mg/L it is generally considered unfit for human consumption. A high level of TDS is an indicator of potential concerns, and warrants further investigation. Most often, high levels of TDS are caused by the presence of potassium, chlorides and sodium. These ions have little or no short-term effects, but toxic ions (lead arsenic, cadmium, nitrate and others) may also be dissolved in the water. 

Even the best water purification systems on the market require monitoring for TDS to ensure the filters and/or membranes are effectively removing unwanted    particles and bacteria from your water. 

The following are reasons why it is helpful to constantly test for TDS:

·         Taste/Health
High TDS results in undesirable taste which could be salty, bitter, or metallic. It could also indicate the presence of toxic minerals. The EPA’s recommended maximum level of TDS in water is 500mg/L (500ppm). 

·         Filter performance
Test your water to make sure the reverse osmosis or other type of water filter or water purification system has a high rejection rate and know when to change your filter (or membrane) cartridges. 

·         Hardness (and Water Softeners)
High TDS indicates Hard water, which causes scale buildup in pipes and valves, inhibiting performance. 

·         Aquariums/Aquaculture
A constant level of minerals is necessary for aquatic life. The water in an aquarium or tank should have the same levels of TDS and pH as the fish and reef’s original habitat. 

·         Pools and spas
TDS levels must be monitored to prevent maintenance problems.

·         Commercial/Industrial
High TDS levels could impede the functions of certain applications, such as boilers and cooling towers, food and water production and more. 

·         Coffee and Food Service
For a truly great cup of coffee, proper TDS levels must be maintained. 

·         Car Washing and Window Cleaning
Have a washer with a spotless rinse? An inline dual TDS monitor will tell you when to change the filter cartridge or RO membrane. 

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*Chart values represent national U.S. averages.  Actual TDS levels for geographic regions within the U.S. and other countries may vary. Click here for the U.S. EPA’s list of National Secondary Drinking Water Regulations.