From my investigations, they only come from the hot tap.

With hot taps, it could be scale - see Water slow.

Fill the bucket to the top with more hot tap water.

Justin turned the hot tap and at once scalded his hand.

He probably fell under the hot tap.the water was at seventy-five degrees centrigade.well above health and safety guidelines.

Slowly pour pitcher of very hot tap water into pan.

He returned to the bathroom and turned the hot tap on.

She walked to the sink and began to run the hot tap.

I shivered and reached for the hot taps but changed my mind.

I turned on the hot tap and began to wash my hands.