Well, if we want more drinking water we might start boiling salt water with electricity.
A cup of water with salt added doesn't get noticeably warm since there's just not much entropy difference in salt water vs fresh water. These days you can reverse the process at very low electricity cost with reverse osmosis.
On grand scheme of pollution, microplastics is basically a fad.
We haven't solved 10 different things that kill us every day. And haven't even started solving 10 another things that is also killing us. After that we can start worry about microplastics.