When I plug stopper at the bottom of the bath tub and turn on the
water, after sometime the bathtub overflows. The overflow drain at the
top of the tub does not seem to be doing it's job. The outflow is less
than the intake. My house is one year old. My builder won't accept
that it is problem. Is this normal and acceptable? Is there any
california safety requirement for bathtubs?

Thanks
Tom