. L% V; s7 H) r+ O5 ?6 nHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe.( ]5 z# \9 C3 d3 K' d' t$ N( m
. W6 U7 M2 ~$ X
Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.