Nitrate accelerated corrosion of lead solder in potable water systems

Although nitrate is generally believed to have little effect on lead corrosion, bench-scale tests in this work revealed that increasing nitrate in the range of occurrence in potable water (0–10 mg/L N) can dramatically increase lead leaching from simulated soldered pipe joints. Lead in water created slightly increased galvanic currents between solder and copper pipe, but nitrate also altered the nature of the attack in a manner that caused solder particles to detach into the water. Chloramine decay and the associated conversion of ammonia to nitrate could create much higher lead contamination of potable water from solder in some cases.

Research highlights
► Higher nitrate concentrations increased lead release from galvanic lead solder.
► Nitrate increased galvanic current between lead solder and copper.
► NO3− from chloramine decay and nitrification increased lead contamination of water.