the u.v. light enhanced with the chlorine is going to destroy everything that might have gotten through the reverse system. >> reporter: if there's any virus, up inside the water -- if there's covid left, this machine is going to get rid of it? >> exactly. let's go taste the water. >> reporter: taste the water. the terminal island plant, has a tasting station, with two faucets to make comparisons. one goes to the households. and the other tap gives you the water that's purified in the plant. this is like wine tasting. this is the water that's delivered to my house, as a resident of the city of los angeles. delicious. okay. i'll put it right here. this is the water that started -- how many hours ago? >> about a day. >> about a day. >> the entire process, about a day. >> reporter: about a day ago, what i flushed down my toilet, has ended up with this? >> yeah.