It has alleged that as women increasingly use the abortion pills at home to terminate pregnancies, flushing the expelled tissue, traces of the pill make their way to water supply, contaminating it.
That's fucked, if true.
One, don't flush any drugs. Take it to a pharmacy and ask them to dispose of it properly.
Two, anything flushed should end up in a wastewater treatment facility. If the waste water is somehow contaminating your drinking water, that sounds like a clean water act violation, and the government should be investigated and fined repeatedly until this is fixed.