6 z4 `( N% y% m9 ?" X- CHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe. / t# B2 i0 ]8 P: Q4 n ) q6 s; {- k! \' H' |" N( mBeside,furnace hot water coil is made of metal. Some of it will come into the hot water.