Showerloop is a water filtration and purification system that recycles shower water in real time allowing you to shower with hot water for a long time but only use 10 liters of water per shower (normal shower = ~6-10l/min) and a fraction of the energy (around one tenth) compared to a normal shower. The device can be installed inside or outside of a shower stall or bathtub. The main components are a pump, sand and activated carbon filters and a UV-lamp. The system weighs around 20kg and is made from transparent acrylic, steel or plastic pipe connectors and copper, plastic or rubber tubing.
The total cost of the most simple version has cost me around 600€ (~$655 US) depending on availability and pricing of local materials and the components used.