Alot of ants come into my house also. they build nest
everywhere. there was twice they had their nest built in the
ceiling cavities in my toilet.
I was so disturbed seeing them crawling in and out of the cracks
and so 1 fine day i took a screwdriver and yank into the
hole.
The diameter of the nest is about the longest cross sectional
length of an adult fist.
The hole was filled with so much ants.
Mind you they are those slow crawling red ants that bite.
So i took a lighted candle and a bottle of deodorant and use it as
flame thrower flamming them.
In 5 mins, the whole nest was gone 
