Handheld TDS Calibration Trust Issues


New member
My old handheld TDS meter was borrowed by a friend a year ago and I have not seen it since. I really wasn't concerned since I have an inline meter on my RODI. But I have been fighting GHA for 3 months now and wanted to make sure that my water was not adding to the problem. So I bought a new handheld TDS meter to double check. The new meter came with calibration solution (1382 tds) and I followed the directions and calibrated the meter.

It was a cheap meter and the batteries I bought for it cost as much as the meter. Now my cheapness has me thinking "How do I really know if it is accurate?"

So after calibrating, I tested distilled water I got from the grocery store and it had a TDS reading of 002. I would have thought it would have been 000.

Then I tested my RODI water and I got a reading of 001.

Finally, I re-tested the 1382 solution and got a reading that bumped between 1382 and 1383.

So what do all you think? Think this thing can be trusted? Here is the one I bought.


Tom G


New member
Remember that it's calibrated at 1382, so it's natural for it to be off a little, 001 for RODI water seems perfect to me. Honestly, calibrated up that high, I probably wouldn't sweat it even if it read my RODI and distilled at 10. Randy does have a great article on Refractometer calibration that explains the whole calibrating in the right place thing perfectly. But basically, I wouldn't worry.