Remove nanoplastics by boiling

If your water is hard (i.e. it contains low of calcium carbonate) then when you boil the water, the lime crust that normally forms on the inside of kettles is caked onto the plastic particles instead, allowing them to fall to the bottom. 

https://www.sciencealert.com/theres-a-surprisingly-easy-way-to-remove-microplastics-in-your-drinking-water