TDS/Latitude relation could be observed in case of surface water where TDS increase with higher temperature due to evaporation. TDS of groundwater depend on many factors including type of aquifer lithology, pH and Eh of the groundwater, temperature and recharge rate.
TDS is not related to latitudes but it is a factor contributed by variations in temperature, pH, composition of the aquifer. TDS of groundwater of equatorial and polar regions can be same but it cannot be same everywhere.
I agree with Dawood answer above" TDS/Latitude relation could be observed in case of surface water where TDS increase with higher temperature due to evaporation. TDS of groundwater depend on many factors including type of aquifer lithology, pH and Eh of the groundwater, temperature"