It seems to be common advice to run the cold water while dumping boiling water down the drain (for example, when draining pasta). A variety of reasons are cited for this, one of which is that it is bad for your plumbing. I assume the reasoning is that the shock to the pipes when they are heated or cooled suddenly causes material fatigue.
- Is there any evidence to suggest that pouring boiling water down the kitchen sink causes pipes to wear out or leak faster?
- If so, is there any evidence that running tap water at the same time can mitigate this effect?
- If so, should you run hot tap water to "prime" the pipes and heat them up more gradually, or cold water to cool the boiling water as much as possible?
Bonus question: if the answer to (1) is "No", is there any benefit to running the tap at all?