"How do we remove feces from our living spaces" and "how do we stop dying from pathogens" are not social problems.
I can’t think of many better examples of social problems than sanitation and public health.
if you do not consider public health a social issue, what do you consider to be one?
How do we maintain large urban communities is a squarely social problems, and parts of it are amenable to technical solutions such as wastewater management, supply chains, large scale agriculture, etc.
Those are perhaps the biggest social problems that humanity has ever faced.