Bradford White water quality specifications
Bradford White publishes water quality requirements in their warranty documentation. Key specifications for tank water heater protection: total hardness not exceeding 25 GPG; iron not exceeding 0.3 PPM; pH 6.5-8.5; chloride not exceeding 250 PPM. Softened water meets the hardness requirement (softeners deliver 0-1 GPG outlet hardness) but may approach the chloride limit in very hard water areas -- softening 20 GPG water with sodium chloride adds approximately 200 mg/L (200 PPM) sodium chloride, approaching the 250 PPM chloride limit. In extremely hard water areas (above 25 GPG), test chloride in the softened output and consider potassium chloride regenerant as an alternative.
Anode rod selection for softened water
Bradford White water heaters include a sacrificial magnesium anode rod to prevent tank corrosion. Softened water has higher conductivity than hard water (due to the sodium ions replacing the removed calcium and magnesium) -- higher conductivity accelerates the electrochemical reaction that depletes anode rods. In softened water areas, expect anode rod life of 3-5 years vs. 6-10 years in hard water. Bradford White recommends inspecting the anode rod at 2-3 years when the water heater is in soft water service. Replace the rod when it is 50% depleted (less than 6 mm of magnesium remaining on the core wire). A depleted anode in softened water leads to tank corrosion -- the Bradford White warranty does not cover corrosion from anode neglect.
Temperature and pressure relief valve considerations
Softened water does not require any changes to the Bradford White T&P valve specification. Use the T&P valve rated for the maximum operating pressure (125 PSI typical) and temperature (210F). The T&P valve should be tested annually by lifting the lever briefly to verify operation -- a stuck valve will not open in an over-temperature event, which is a safety hazard. Replace the T&P valve every 6 years or when testing reveals sluggish operation.