+ B- h- ~9 T; M' Z6 \; s: eHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe. 9 |( r5 U/ O' j$ J4 Q; H% f7 V/ h3 S6 K* p, X) M% K7 j
Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.