, b$ E% t+ }5 o& z6 pHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe.8 d8 H# ^+ \1 C: R& y3 H, ?
" s+ N2 j4 }' F- I0 K m M
Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.