Jay,

Yes the dip tube is installed by default. But brand new products are
sometimes not put together correctly so it might be the dip tube.
Your local library will have books on home repair and maintenance. You
need to buy a voltmeter and learn to use it if you don't have one. Your
problem predates the new water heater so I suspect you have a leak, either
in a pipe or in a single handle faucet. I suspect that you bought a new
water heater when there was nothing wrong with the old one. Welcome to the
DIY Homeowners Club, we all make stupid mistakes. It's how we learn.

Dave M.