  In this article, following the arithmetic case, we define the notion of Wach
modules in the relative setting. Over an unramified base, for $p$-adic
representations admitting such structures, we examine the relationship between
filtered $(\varphi, \partial)$-modules and Wach modules. Further, we show that
for certain class of crystalline representations (in the sense of Brinon), one
can recover filtered $(\varphi, \partial)$-modules from Wach modules.
