Design Problem

Typical “linear” shower systems are wasteful. They take fresh potable water, heated to a comfortable temperature with electrical or fossil energy, and then use it once, dumping the resulting grey water and heat energy down the drain. The longer the shower, the bigger the associated energy and water footprints become.

Design Solution

Showerloop is an open source water filtration and purification system that recycles shower water in real time. The system allows you to shower with hot water for a long time, while using only 10 liters of water per shower (normal shower = ~6-10 liters/min) and a fraction of the energy (around one-tenth) compared to a normal shower. By reusing heated water, Showerloop helps us to enjoy long hot showers without the waste.

Showerloop 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
• copper, plastic, or rubber tubing

The total cost of the most simple version is around $650 USD, depending on availability and pricing of local materials, and the components used.

Assembling the filters.

The filters typically last between one to two years with daily use, though their lifespan depends on the behaviour and general dirtiness of the user/s. The sand filter can be washed, and the activated carbon or AC can be regenerated (at high temperatures > 500 degrees C) or simply composted. The UV lamp should last for thousands of hours but can be recycled and replaced like any other compact fluorescent lamp.

Complete project build instructions are available on Instructables.

Design Constraints

The system was ingeniously designed to balance filtering capacity with form. The filters must be big enough to adequately cleanse grey water. But the system must be small enough to fit into a normal bathroom, and its installation should minimize the disruption from a bathroom retrofit. Showerloop’s current design keeps a slim profile using two “flow regulators”. The first one splits the flow of grey water in two prior to filtration. The second recombines filtered water into as single stream prior to UV sterilization. This design obviates the need for single large-diameter filter, allowing two thinner filter tubes to do the job.

The basic build of Showerloop is incredibly modular in terms of placement, materials selection and aesthetics. The only constraints come from the ideal filter dimensions and the power output of the UV lamp, both of which are explored in the bachelor thesis, ShowerMagic: A Hygienic and Eco-Efficient Real Time Greywater Reuse System for Showers.

Energy and Water Efficiency

The system requires an initial input of about 10 liters of hot water, which can then be cycled until the heat dissipates and the water cools down. The energy consumed per shower comes from the energy used to heat the 10 liters to a comfortable temperature, and the energy used by the pump to move water through the filters and back to the showerhead at pressure. As illustrated in the below graph, the longer you shower with Showerloop, the more energy (and water) you have saved compared to a conventional shower of the same duration.

This post includes material excerpted and edited from the Instructable by Showerloop under a Creative Commons Attribution-ShareAlike 2.5 Generic license (CC BY-SA 2.5), which is published here under the same license.