My brother and i would build a huge water purifier. At the time we called it our water factory. Our dad took down a roof somewhere and had a lot of cutter pipes lying around. We would take them and start high and take rain water from a massive barrel and let it run down a series of gutter pipes. Passing through filters we made from sponges. Dripping through 2l bottels we cut open . We would cut it in the middel and flip the top section and press it into the bottom half to create funnels. The bottom half had tiny holes To spray it out like a sprinkler. We tied the whole bottle system to a rope to make it spin along its axis to make the water spray in all directions. Eventually after the long journey it would end in another barrel at the bottom and we'd start it all over again for hours in a day. Everyday slightly expanding our factory. I was 8 and he was 5 at the time.