Up to a point, ours must have done that too.
I thought she got the point of the water question wrong - she asked where we got our water from, and I said, from the tap, but she said, no, where does the water supply come from - aqueduct, well, etc.? I'm sure the purpose of that question is to establish how many households have a mains water supply.
There is some data that is used for development indicators (as in the UNDP reports) that you could not obtain through observation. Or maybe these come from the ENHOGAR surveys that are more detailed.
In any case, the process confirmed the widespread perception that the basis for a lot of statistics is shaky to say the least - how many people who are illiterate or semi-illiterate will have replied "yes" to the "Can you read and write?" question?