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TDS is lower then Total hardness

Is it possible, the total Hardness is higher then Total Dissolve Solids (TDS) of the same water.

Anwar Hossain
- Dhaka, Bangladesh
February 2, 2011

Hi, Anwar. If the two parameters use the same units I can't see how that is possible. Please put your question into context. If this a question on a homework assignment? Is a lab reporting such results? Thanks.

Regards,

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
February 2, 2011

It is not possible. However, if you are measuring the TDS with a TDS meter, the reading is probably incorrect because it actually measures conductivity, not TDS. The most accurate way to measure TDS is to evaporate a filtered sample to dryness and to weigh the residue.

Lyle Kirman
consultant - Cleveland Heights, Ohio
February 3, 2011

If the hardness is being reported in mg/l CaCO3, but is present as magnesium, the results you describe are possible.

Dave Wichern
Consultant - The Bronx, New York
February 13, 2011

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