How does Rohinton Mistry use imagery in Swimming Lessons?

Imagery:

" 'Arré forget your gunga-bunga!' howled Rustomji. 'That stinking lavatory upstairs is leaking again! God only knows what they do to make it leak. There I was, squatting - barely started - when someone pulled the flush. Then on my head I felt - phuk - all wet! On my head!"

"With a thunderous clap the rain started to fall."