If a building has an indoor pool, and there's a lightning storm,
should swimmers get out of the pool even if the building is metal? 
One is safe from a storm inside a car since the charge stays on the
outer shell of the car, right?  (Or is it because of the rubber tires
that keep the car from being grounded?)  If so, it seems that one is
safe in an indoor pool from an electrical storm, even if pipes leading
into the pool are effectively grounded.

Hello there

Everybody out of the pool.

The warnings abound.  Get out of the water, indoors or out.  That
includes taking showers, hand washng dishes, or anything else which
has you in water.

"Avoid higher elevations; wide-open areas such as sports fields; tall,
isolated objects such as trees, poles and light posts; metal fences
and bleachers; open vehicles, including golf carts with roofs;
unprotected open buildings such as picnic pavilions and bus shelters;
and water-related activities, including swimming in indoor pools." -
From University of Illinois at Chicago Office of Public Affairs  -
http://www.uic.edu/depts/paff/opa/releases/2001/lightninghazard_release.htm

You will find in that srticle that lightning kills more people in the
US each year than hurricaines and tornados combined.  The author is
considered the leading international authority on lightning strike
injuries.

As for being safe in a car.  Yes and no.  Your basic premise is right
in that it is the metal shell which protects you, but there are
certain other criteria which must be met as well. - - "A reasonable
second choice is a vehicle with a solid metal top and metal sides.
Cars are safe because of their metal shells; convertibles or vehicles
with fiberglass or plastic shells are not safe. Close the windows,
lean away from the door, put your hands in your lap and don't touch
the steering wheel, ignition, gearshift or radio." - quote from same
website as above.

This article from the National Athletic Trainers Association carries
the same warnings:
http://www.nata.org/publications/otherpub/lightning.pdf - a PDF file,
Acrobat Reader needed.

Whether the building is all metal or not, whether pipes are grounded
or not grounded, whether they are non-conductive plastics or even
wooden (if such things still exist)  the lightning charge follows the
water.  And there are other thing which may carry lightning to the
pool besides just the pipes.

This next quote is specific for pools, indoor and out: - - "Question:
Is it necessary to evacuate a pool during lightning?
Yes. There are a few cases in and around swimming pools every year in
the U.S. During the summer of 2000, two boys were killed at an outdoor
pool in Florida. Documented cases of indoor pool lightning victims are
scarce. The whole indoor or outdoor pool complex should be considered
unsafe during lightning unless proven otherwise. The open surface of
the pool is one factor, but the power, plumbing, and mechanical
connections to the pool are a very important factor, too. Water and
electric lines are very good conductors. The most likely scenario is
for lightning to hit a utility pole outside a pool. The current then
travels through wires into the pool area. Every pool has a pump, and
the pump is designed to move water. That connection can be the site of
a transfer of lightning current from the power system into water in
the pool, then to wading pools, the shower area, and anywhere there is
standing water. Everyone in contact with water in the complex could be
a lightning strike victim. Lightning safety experts recommend staying
out of the water for 30 minutes after the last flash or thunder.
Studies found that waiting 30 minutes eliminates most lightning risks
as the storm leaves the area."  - - The quote is from a FQA about
lightning safety where you will find a ton of other information as
well.  Website by the VAISALA	 Group -
http://www.lightningstorm.com/tux/jsp/faq/index.jsp

And last: - "Indoors vs. Outdoor Aquatic Facilities:

"The question often rises about whether or not these same procedures
need to be followed during a thunder and lightning storm when
operating an indoor facility. It is almost impossible to totally
protect a facility's electricity network from the damaging impact of
lightning strikes. A facility's lightning protection system is
designed to control the current provided by a lightning strike through
a specific conductive path, thereby eliminating the chance of fire or
explosion within non-conductive parts of the protected building.
Lightning protection does not prevent a strike, but provides a safe
path for the dangerous current to follow to ground. According to the
American Red Cross, telephone lines and metal pipes can conduct
electricity and the use of telephones or any electrical appliances
should be avoided during a thunder and lightning storm. They also
advise to avoid taking a bath or shower, or running water for any
other purpose. Based on this information, we advocate that the same
principles that pertain to outdoor aquatic and recreation facilities
should be followed for indoor facilities as well." - Quote from
"Emergency Procedures During Thunder & Lightning Storms"  Website of
Lifesaving Resources
http://www.lifesaving.com/issues/articles/20thunder_lightning.html

So when a storm comes, get out of the pool and stay away from any standing water.

Search - Google
Terms - lightning safety swimming pools

If I may clarify anything before rating the answer, please ask

Cheers
Digsalot

Thank you for your answer.