Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_28818 ( "Hydrographic Basin" text, "Surface Area (km 2 )" real, "Rainfall totals (million m 3 )" real, "Evapotranspiration (million m 3 )" real, "Surface water runoff (million m 3 )" real, "Groundwater discharge (million m 3 )" real )

### Question ###
What is the lowest overall amount of rainfall totals (million m 3)?

### Accurate SQL ###

SELECT MIN("Rainfall totals (million m 3 )") FROM table_28818