I’d still call it out on a home inspection. Here’s the IRC and the commentary (I realize ya’ll don’t go by that in the Republic of CA ;-)).
E3608.1.1 Metal underground water pipe. A metal underground
water pipe that is in direct contact with the earth for 10
feet (3048 mm) or more, including any well casing effectively
bonded to the pipe and that is electrically continuous, or made
electrically continuous by bonding around insulating joints or
insulating pipe to the points of connection of the grounding
electrode conductor and the bonding conductors, shall be considered
as a grounding electrode (see Section E3608.1). Interior
metal water piping located more than 5 feet (1524 mm)
from the entrance to the building shall not be used as part of the
grounding electrode system or as a conductor to interconnect
electrodes that are part of the grounding electrode system.
** Commentary:** Any metal water pipe in contact with the earth for 10 feet
(3048 mm) or more is considered a grounding electrode.
It is often thought that only the main water service piping
fits this description, but any metal water pipe, such as an
irrigation pipe or pipe from a water well, if buried in the
earth for 10 feet (3048 mm) or more, must be bonded as
part of the grounding electrode system. The pipe could
be of any material such as copper or steel because the
code does not mention the type of metal. In many
houses, a water meter, water-pressure reducing valve,
or similar equipment is installed in the water supply line.
A bonding jumper of the same size as the grounding
electrode conductor is installed around such devices because
many of these devices are made of
nonconductive materials. In many cases, when the device
is removed and/or replaced, the grounding electrode
is disconnected. A useful practice is to leave
enough slack in the bonding jumper around the device
that the jumper will not have to be taken off the piping in
the event the device is replaced.
The code assumes that the first 5 feet (1524 mm) of
water piping, measured from the point that the piping
penetrates an outside wall or floor slab on grade, will not
be disturbed or altered by plumbing work. Any piping beyond
5 feet (1524 mm) into the building is more likely to
be altered such that electrical continuity is lost. This alteration
could take the form of the installation of plastic piping,
nonconductive components (e.g. water filters), dielectric
fittings or the removal of grounding clamps.
**A supplemental grounding electrode is always
required when a water pipe electrode is used. **The most
commonly used supplemental grounding electrode is the
ground rod. That is why in so many dwellings a grounding
electrode conductor is run from the service equipment
to the entry point of the water pipe and another
grounding electrode conductor is run to a ground rod.
The ground rod is quite often driven into the ground close
to the service equipment. A grounding electrode conductor
that connects the service equipment to a ground rod,
pipe or plate electrode and connects to no other elec-
trodes is not required to be larger than size 6 AWG copper
or 4 AWG aluminum (see note to Table E3603.1 and