7 t1 [2 \" F6 `: m% R7 kHot 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; X2 D( k, |& J8 g( K8 o9 w6 j: A+ ~$ k8 h8 o
Beside,furnace hot water coil is made of metal. Some of it will come into the hot water.