GreywaterPoster2 (Energy Hub poster, Dec. 2013)


The Issue

Valuable clean drinking water is literally being flushed down the toilet every time you use the bathroom, wasting water and money.

Overall Goal

The goal of this project will be to construct a toilet that gets all of its water supply by recycling used water from the shower and sink.


9/30 – Compile Resources, Discuss Design Challenges

10/7 – Develop Design10/14 – Develop Design

10/21 – Finalize Design and Materials Needed

10/28 – Inventory Materials, Begin Fabrication

11/4 - Continue Fabrication (Water Collection / Filtration)

11/11 - Continue Fabrication (Pumping Collected Water)

11/18 - Continue Fabrication (Integration into Toilet)

11/25 - Continue Fabrication, Work on Presentation

12/2 – Complete Fabrication, Finalize Presentation

12/9 – Demonstrate Prototype


Finalize Design and Order Materials, October 21st DONE

Complete Fabrication, December 2nd

Demonstrate Prototype, December 9th

Resources Needed

A generous grant from the Wisconsin Energy Institute will provide funding for our project. The Physics Garage will provide the space and equipment needed to develop our project.

Summary of Sources

How Toilets Work:

Below is some general information on how toilets work. This will be helpful in making sure our new design still has the proper functionality.


These sources will be helpful in determining how to get the collected water into the toilet to be reused. We are unsure whether we are going to be using electric or manual pumps. Electric pumps will need to have a power supply but would make the system easier for the consumer to use. Manual pumps will be cheaper and “greener” but will require the user to put in some work.


There are five main type of sediment filters that are most useful:

• Spin-down filter strainers & wye strainers

• Centrifugal separators

• Cartridge filter systems

• Backwashing media filters

• Ultra-Filtra on (UF) membrane systems

Read more:

Spin Down Filter Strainers with Mesh Screens

Spin down filters use screens of varying sizes to remove large sediment and grit from water. A typical practical size for home water wells is either 60 (250 microns) or 100 (150 microns) mesh.

Wye Strainers

A wye strainer has an internal screen with a large 20 mesh screen. It is used to keep large sand or foreign objects out of piping systems. A hose bib or valve can be installed on the screen "Y" section to allow flushing of the strainer.

Read more:

Centrifugal Separators

In a centrifugal sand separator the water rushes through the device and centrifugal force slings large particles, sand, debris and sludge outward to the separator wall and downward in a spiral motion.

Gravitational force pulls the separated solid particles downward past the spin trap plate into the solids holding chamber. Cleaned water then rises through the vortex locator and returns back to the plumbing system.

These systems have no screens, slotted baffles, moving parts or filter media so there is no pressure loss.

No maintenance is required; however periodic opening of the purge valve is necessary to flush out accumulated solids. Purging can be done manually or an automatic flush valve can be used.

How It Works: Submersible pump in well is controlled by pressure switch. When well pump runs water flows through centrifugal separator and solids are separated out.

Read more:

Sediment Backwash Filters

• Removes sediment and turbidity with no filter cartridges or maintenance

• Natural zeolite mineral filters water to 5 micron range

• Auto backwash & rinse keeps media clean

• Little or no pressure drop through filter

• Rugged media lasts for years

• Lighter than sand but filters finer

• Lower backwash flow rate requirements than traditional sand filters

Read more:

What has been done before?

These ideas have been done before, but we can make it better.

Group Members

Project Update (11/15/13)

The project is coming along nicely. This week we will be putting our shelf together and connecting the water collection and storage bins to the filter, pump and toilet. We will also continue to develop our arduino code to be able to control the pump based on how much water is in the toilet.

None: Grey Water Toilet (last edited 2013-12-09 18:43:53 by DuncanCarlsmith)