Dear Omonona,

We have analyzed the relationships between water mineralization and electric conductivity (EC) of natural river waters in the Aral Sea Basin for last decade and have revealed that 1 mg of water salinity was equal to 1.41-1.52 µS/cm. The water quality standard for human consumptions around the world of 1 g/L in ASB basin will be reached when EC equal to about 1410-1520 µS/cm depending on the river basin. These findings will be published very soon in Book of abstracts of SETAC Orlando 2016 annual conference.

Look also at our article: Saving freshwater from salts. Science 351(6276):914-916 · February 2016.

https://www.researchgate.net/publication/295912642_Saving_freshwater_from_salts?ev=prf_pub

With best wishes

Bakhtiyor

Article Saving freshwater from salts

 Simple relation  using TDS (mg/L): EC(us/cm) X0.67

EC: There is no conversion for electrical conductivity.  The standard EC mode is KCl.)

TDS - NaCl: 0.47 to 0.50

TDS - 442: 0.65 to 0.85

TDS - KCl: 0.50 to 0.57

If your water analysis indicates the TDS and the electrical conductivity, then it should be possible to establish the following relation.

+ 500 ppm correspond to 1000 μS / cm or 1 EC. When using a NPK meter, the relation between TDS and electrical changes to the below stated value.

+ 700 ppm correspond to 1000 μS / cm or 1 EC

 Read more: http://www.lenntech.com/calculators/tds/tds-ec_engels.htm#ixzz4Nh9MD337

Best publication is USDA Handbook 60 for thorough reference ...

Salinity can be measured approximately from TDS and EC. Salinity can not be measured from Cl alone.

Electrical conductivity and concentrations of total dissolved solids (TDS) are not related to each other one by one. But in dilute solutions (such as natural water) between these two factors are as follows:

TDS = 0.5 EC

The relationship between TDS and EC for any water sample due to its physical and chemical properties vary.

the relationship between TDS and EC is highly varying in response to type of medium , we use . Well said Ebrahim.

The relationship between TDS and EC usually varies depending on the specific sample

Salinity can be estimated from EC very simply.

First, convert values EC to water resistivity.

Conductivity values, EC, in mS/cm are converted to electrical resistivity values, rw, in Ohm.m by:

rw (Ohm.m) = 10* (1/ EC (mS/cm))

Subsequently, the values are corrected at a reference temperature of 20°C by

the expression (Sorensen and Glass, 1987):

rw20 = rw(Τ) [1 + α (T - T0)]

Where:

T = water temperature (°C)

α = temperature coefficient equal to 0.0177 1/°C (Beklemishev, 1963)

T0 = reference temperature equal 20°C

rw = water resistivity measured in field

rw 20 = water resistivity corrected at 20°C

For a reference temperature equal to 20°C, it is possible, for salinities below 10 g/l, to estimate the water salinity from water electrical resistivity using the relation:

C = 6 / rw20

Where C is the salt content (NaCl equivalent) in g/l

Working with conductive values TDs = .0009c^2+.0387c+.0022 (Clavier et.al 1984) c= conductivity of fresh water.

Water containing TDS concentrations below 1000 mg/litre is usually acceptable to

consumers, although acceptability may vary according to circumstances. However, the

presence of high levels of TDS in water may be objectionable to consumers owing to the resulting taste and to excessive scaling in water pipes, heaters, boilers, and household appliances. Water with extremely low concentrations of TDS may also be unacceptable to consumers because of its flat, insipid taste; it is also often corrosive to water-supply systems.

Electrical conductivity is a measure of water capacity to convey electric current. The most desirable limit of EC in drinking water is prescribed as 1,500 μmhos/cm (WHO, 2004). The EC of the groundwater is varying from 64.02 and 2199.57 μmhos/cm with an average value of 514 μmhos/cm. Higher EC in the present model of sand storage reservoir indicates the enrichment of salts in the two samples of water.

Dear Mr. Omonova,

A quick way of estimating Salinity is to use a conductivity meter and read off the electrical conductivity (EC). The idea being that a salty solution, because it is full of charged particles will conduct electricity. Most conductivity meters give readings in micro Siemens per cm (µS/cm). Most fresh (drinking) water will have less than 100 µS/cm conductivity (EC). 

Relation between conductivity (EC) and TDS: TDS is more precisely measured in the laboratory by evaporating a measured sample gently to dryness then calculating how much solids are left. Conductivity is usually given as µS/cm which measures the ability of the sample to conduct an electric current.

There is no exact but an approximate relationship between conductivity as µS/cm and TDS as ppm. In water with a higher proportion of sodium chloride to get TDS in ppm just multiply the EC µS/cm reading by 0.5. For most other water (like in hydroponics solutions) use a factor of 0.67 or 0.7 instead.

Relation between EC and chloride concentration: The electrical conductivity [EC] and chloride ion concentration values of ground water samples (in Mexico) were found to be related by the linear equation: [Cl-] = 4.928 EC (R> 0.94). [Reference: Cien. Inv. Agr. 39(1):229-239. 2012].

Hope the information is interesting and useful to you.

Dear Omonona,

the literature about correlations for salinity evaluation by EC measurements is very abundant. However, you are asking for an assessment which includes TDS, i.e., total dissolved particles charged and not charged. You can obtain an evaluation of TDS by osmolarity measurements (Osmotic pressure, boiling temperature variation, melting temperature variation, the so called colligative properties of solutions). At the same time, you need information about the presence of charged solutes as chloride ions. You can consult a paper I published in 1980.

https://www.researchgate.net/publication/256177570_Evaluation_of_ionic_strength_and_salinity_of_groundwaters_effect_of_the_ionic_composition

Best wishes

Sabino

Article Evaluation of ionic strength and salinity of groundwaters: e...

The same formula should serve for the two environments.

What is the source of this formula?