The quality of well water varies greatly especially in the RG Valley,  Mexico & all of Texas. Good quality water may be used extensively. Very poor water should never be used. There are many types of water which may be used in a restricted manner during an emergency and with proper treatments.   As such, they may be valuable.
In order to use water with greater benefit, essential characteristics must be known, so as not to damage land and crops.   
TSS composition is important for proper management: CATIONS of Na, Ca, Mg, K and ANIONS of Cl, HCO3, SO4 and B. Important characteristics and their meanings are given below:

TOTAL SOLUBLE SALTS:
Electrical Conductivity (E.C.) measures the total soluble  (dissolved) salts (TSS) as mmhos/cm,  ( 1.0 E.C. = 640 ppm ).   PPM = parts of a salt per million parts of water   (10,000 ppm = 1%.   Sea Water contains about 3% salt.)
      0 -   299  Very Low                  Should be no problem
  300 -   699  Low                           Seldom of any concern
  700 -   999  Medium                    SAR rating is best guide
1000 - 1199  Moderately High      Use good water & soil management
1200 - 1499  High                          Water & Soil management necessary
1500 - 1799  Very High                 Emergency use - requires soil treatment
> 1800   Extremely High               Maybe Very harmful to soil & plants     
                                                          with repeated use. Treat water & soil.

The above table gives an average idea on water quality. Below are other factors which must be considered in making practical decisions:

  1. How much salt is in the soil to begin with ? (Soil salt checks that identify Soluble Salts are important when mediocre waters are used)
  2. What is the soil type ? (Drainability is extremely important.)
  3. What is the rainfall between irrigation's ? (With good internal  drainage, salts can be washed below the root zone.)
  4. What is the method of application ? (Pan, row, drip or sprinkler)
  5. How salt-tolerant is the crop ?
  • Highly Salt Tolerant: (> 4.0 E.C) Bermudagrass,   
         Beets, Spinach,  Many Cotton varieties, Barley,       
         Asparagus, Date Palm.
  • Medium Salt Tolerant: (2.0 - 4.0 E.C) Alfalfa, Tomatoes, Broccoli,  Cabbage, Celery, Peppers, Lettuce, Corn, Oats, Grain Sorghum,  Potatoes,  Sugar Cane, Squash, Cucumbers, Watermelons,  Soybeans, Grapes, Radish.
  • Sensitive to Salts: (< 2.0 E.C) Citrus, Berries, Avocado, Apples Beans, Carrots, Onions, Peas, Papaya, Peaches, Pears, Plums

Treatments can only aid salt leaching by making chemical changes. Salts must be physically flushed below the root zone. To do this, the soil must be permeable and sufficient water must be applied.
CHLORIDES & SULFATES are the most predominate kinds of salts. Chlorides are more harmful. They are highly soluble & move easily with the water. Cl > 300 ppm may burn plants & roots on contact.

SODIUM affects the soil in an undesirable manner. It tends to make the soil hard and impermeable, thus the leaching of salts is difficult. Soluble Calcium has the opposite effect. The amount of  Sodium that will be absorbed by the soil from the irrigation water depends primarily upon the relationship between Sodium and Soluble Calcium: SAR - Sodium Adsorption Ratio.  A high SAR requires addition of high amounts of soluble calcium. The need for calcium also depends upon total salts in the water, as well as bicarbonates & sulfates. Soil soluble & extractable calcium must be known also to manage salts properly.
 

Page 1 of 2