  Results of the E\"otv\"os Pek\'ar and Fekete (EPF) equivalence test were used
by Fischbach and coworkers in 1986 as an argument in favor of a hypothetical
fifth force. Although this hypothesis was abandoned in view of the negative
experimental results that followed, we still miss plausible explanation of the
EPF results. This situation motivated us to investigate the EPF test in terms
of gravity gradients. This paper presents arguments that the results can be
explained as a classical systematic effect related to the ambient gravity
field. We found that gradients of the ambient gravity field caused a false
equivalence violation signal. Firstly, this was due to the time variation of
gravity gradients, in spite of the fact that the experimenters were aware of it
and designed a method to cancel it. Second, the EPF samples had different
shapes and therefore the gravitational force was necessarily different in a
constant, but inhomogeneous gravity field. We demonstrate that there is an
ambient gravity field where these effects can fully reproduce the EPF results.
