In the installation or repair of plumbing intended to dispense water for human consumption, a person shall use only pipes, pipe fittings, plumbing fittings, or fixtures that are lead–free. In the installation or repair of plumbing intended to dispense water for human consumption, a person shall use only solder or flux that is lead–free. Only the individual pipes, pipe fittings, plumbing fittings, or fixtures that are installed or repaired may be considered when calculating the weighted average lead content.