Nectar in a Sieve presents a nuanced view of the caste system in India. It does not necessarily "take a stand" on the system, but rather tries to show in the context of families, generations, and change.
Caste is everywhere in Nectar in a Sieve, but it does not overwhelm the story. Overall, we see that the caste system holds sway over the older generation much more then the younger. One clear example of this is that Rukmani is content within the caste system, but feels her children should not get jobs at the tannery and ignore their caste. They do so anyway, as they are not wedded to the system in the same way.