Can I Test My Water Hardness With A TDS Meter?

Are you trying to use your TDS meter to measure your water hardness? You cannot do that. The problem with trying to measure hardness by measuring TDS is that TDS is made up of much more than just hardness ions.You also can not use a TDS meter to figure if your softener is working correctly. You want to use water hardness test strips to test for water hardness.