9 D+ E6 A/ p1 w7 O% n: D# \1 BHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe. & ~" I- i N( E% S9 m4 ^ * t9 i6 ?& G7 w4 CBeside,furnace hot water coil is made of metal. Some of it will come into the hot water.