Eli5 – why is the first few moments of every shower cold, even if I already warmed up the water via the bath first?

Question

Don’t understand how the plumbing works. I keep thinking the water should already be hot.

In: Engineering

Answer 1

The pipes are usually cold and often an on demand water heater needs to turn itself on. The closer the bathroom is to the water heater/tank, the faster the water will heat.