V% M8 _# C9 I& y% ?' }( Q& Z! JHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe.* F& [: w/ z+ Z3 {% R9 s
) Y, Q( B6 y! ^/ ZBeside,furnace hot water coil is made of metal. Some of it will come into the hot water.