As already advised, you shouldn't put house spiders outside, they will not survive. House spiders live and breed indoors, where the warmth and lack of moisture suits them.
They will get in through your roof space from outside, and breed and evolve into house spiders.
Spiders do not come up through drains, they are far too fastitidious to go anywhere near a grotty drain, even assuming they could negostiate an 'S' bend full of water. They find themselves in sinks and baths because they fall in during their travels, and can't climb out. If you can't touch them, drape a towel over the edge, trailing along the bottom of the bath or sink, and leave them for a few hours, they'll be gone when you return.