If it was built by a contractor or developer,
they should resolve your problem at no expense.
Most warrant their work for 1 year or more. Some
states require that they do.
Most states have disclosure laws, if you purchased
from a private owner, you should have received a
disclosure statement. If you used a realtor they
normally employ an attorney and take care
The water could be from any number of reasons.
Was drainage tile installed around the foundation?
Since it's coming in 1/2 way up the wall,
(I'm assuming only when it rains)it may just be
migrating through loose backfill, but that would
Water normally comes through a wall due to
pressure from the ground water table. Think of
your basement like a boat with holes in it,
suspended just above the water.
All is fine until it rains and the water starts
to rise. If the water gets up to the holes, it
begins to come inside. The drain tiles that should
be installed around your foundation, should
prevent the ground water level from rising up to
the holes in your basement walls.
I have seen an instance where a house was built on
an underground spring. Hope that's not the case.