What an amazing concept! Simple backyard projects like this can be fun to use and rewarding to build. PVC is easy to find and cheap to buy at most local hardware stores. Unfortunately, PVC isn’t very green and there aren’t many(if any*) environmentally friendly /cost effective alternatives. Your DIY PVC water park project may not use as much PVC as the construction industry, but we should be conscious of our decisions and aware of their impact on the environment. Alternatively, dancing in the rain is free. Have fun and enjoy your water park!