Not all water is created equal. When we drink different waters, we experience their distinctive qualities as different flavors. The mineral, carbon dioxide, and oxygen content of water vary substantially, and affects your plants.
Three key measurements of the water composition are its “alkalinity”, its “pH” and its content of “dissolved salts”.
Alkalinity is the ability of the water to buffer acids. When water contains dissolved solids/minerals the pH is not affected as much by the addition of fertilizer. When water is pure and contains no minerals it is called soft water. This water has little or no buffering ability so its pH is very changeable.
pH is a measure of acid-alkalinity balance. A pH between 5.3-6.5 is what plants like best. The pH of tap water may change seasonally. Test it regularly. The pH changes when the water company flushes its system.
Dissolved salts are the mineral content of the water and is usually expressed as parts per million (ppm). This can be measured using electrical conductivity (EC) meters. A reading of 125-150 ppm for your water is a good starting point because it represents some buffering ability , but not to much that large amounts of minerals have to be added to adjust pH.
NOTE – When you irrigate the plants make sure that you don’t shock the roots with water that is either too cold or too warm. Make sure that the water is in the temperature range of 65-75 F or 18-24 C.