HM Digital TDS-EZ Water Quality TDS Tester. 0-9990 ppm Measurement Range , 1 ppm Resolution, +/- 3% Readout Accuracy. Use to measure total dissolved solids in water.
Using RO (Reverse Osmosis) or DI (Distilled) Water allows you to build your water profile from the ground up, creating exactly the profile you’re looking for. If you filter you own water a TDS is handy. If you purchase RO or DI water from the store (instead of getting a filter), I would still suggest picking up a TDS meter. Some water processors add minerals back for flavor. A TDS meter will allow you to make sure you’re getting what you want.
Update: Since this post was published the price, availability or promotion has changed. Check the product page for current description, price and availability. Also: Today’s Deals on Amazon