The best replacement for tds is conductivity.

The best alternatives to tds are rated as following:
★★★★★  conductivity
★★★★  ec
★★★  ppm
★★  charter
★★  tss
★★  hardness
★  resistivity
★  turbidity
★  tcs
★  salinity
★  dps
★  tid
★  water hardness
★  conductivity meter
★  microsiemens
  gh
  specific conductance
  glacors
  service tax
  hardness of water
  alkalinity

Your alternative for tds is not listed? Suggest!
Speaking about tds, one probably shouldn't forget about service tax.

Other search terms related to tds and their ratings are:
★★★★★ service tax
★★★ pan
★★ pan card
fixed deposit
You have in mind a companion for tds and it is not yet here? Propose!



Google Trends

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tds
conductivity
ec