If a toilet paper full of sperm in toilet bowl and i flushed water 3 times. is there any risk of pregnancy for a woman using bathroom after this act ?(if water touches her while flushing) .i flushed 3 times to make sure everything is clean?

I cannot find is reasonable to believe sperm could survive in this setting, find their way up into a woman's internal genitals and proceed to establish a pregnancy. They are fragile and become immobalized quickly when they are not in a favorable environment.

Sperms are dead and long gone in your scenario. No chance of pregnancy as they have to enter INSIDE the vagina within 10 mts of ejaculation-

No risk of pregnancy.