Not usually, at least not by BS 7671. Other standards/guides/advise may differ of course (including manufacturer's instructions)

Sometimes it's a quick and dirty means of making things are bonded (e.g. using the water pipe as a bonding conductor for the gas, or for heating pipes if they're sunk into an old solid floor or some such) but it's hardly the ideal approach.  Occasionally it's thought that extra bonding might help protect when things are partially dismantled (e.g. during routine boiler maintenance), especially if worried about a fault elsewhere in the installation at the same time - but the likelihood/magnitude of such things are getting to be beyond what BS 7671 considers.

    - Andy.

Plumbers' bonding!

We also have it at every sink, bath, and wash hand basin, but that was 15th Edn.

I asked a plumber who wanted me to do that underneath the boiler. I asked why, he said its the manufacturers instructions. I looked through the instructions, not a mention of it. It's something they thought needed to be done, but hasnt ever been required.

The new Worcester 8000 boiler has, like most worcester boilers, a wall jig to pre-plumb the pipes. These usually consist of a steel bar with brass valves through holes in it bolted to the bar. So pretty electrically continuous. Despite this the 8000 has an extra copper bar connected to to each valve. couldn't find a pic but got a screenshot from an unboxing video;

• Edit; since a fair few bits within the boiler are now made of plastic, and with regards to AJJ's mention of maintenance, it sort of makes sense to have good continuity across the pipework.  Also, instructions say the first meter or so must be in metal, before plastic pipes can be used.