3 v$ Y3 r8 H4 p$ i0 xHot water has went through all your home's internal pipes whereas cold water comes "direct" from your local reservoir. Which should be pretty safe. * [/ O( V- r0 X3 j1 o 2 \$ V8 X$ p5 ABeside,furnace hot water coil is made of metal. Some of it will come into the hot water.