Approximate Cost for Greywater System

I downloaded the Greywater expense Excel Spreadsheet from the Oasis website.  Using Google's shopping search engine, I found a price for each part listed on the Excel worksheet.  Using this method, the PVC version approximate cost is $255.

Here's a link to the Altered Excel Spreadsheet

Preliminary Site Assessment

I started reading Create an Oasis with Greywater by Art Ludwig.  It is an excellent resource and I recommend it if you are interested in creating a greywater system.  The book contains an outline in Appendix A for organizational purposes.  This outline has helped me focus because it is easy to become overwhelmed by the various possible systems. 

Since wetlands exist naturally here in the northwest, I have decided to construct a wetland filter using native aquatic plants and pea gravel in a rain barrel that I found discounted for $5. 

Preliminary Site Assessment

Greywater System Goals: Reuse the washing machine’s wastewater for the toilet and for the washing machine, filter out the toxins that collect in the wastewater from the washed clothes and for demonstration.  
    This will be a two step process.  I first want to construct the wetland filter and test the water purity.  This will determine whether or not it is necessary to purify the wastewater further with ultraviolet light, which seems to be a common method to use before indoor usage. 

Perfection Standards: High.  The wastewater must be purified to a high degree to prevent anaerobic conditions. 

Location: Seattle, WA

Water System:

Rainwater and runoff:

Existing wastewater treatment facilities:  Assumption --Sewer, which ultimately dumps into the ocean. 

Population of water users:

Climate: Rainfall
Evapotranspiration

Forces of nature:  Heavy rains during winter.

People:

Regulatory Climate: 

Economics:

System used:  Wetland.  One thing to keep in mind is that after time sometimes the wetland filter can become clogged and then needs to be cleaned out, usually by backwashing it with water.  This is what most people, who have built a similar system experience after about a year or two of usage. 
   

Clearing the Grey

The average American Citizen uses 80-100 gallons of water a day and the average African Citizen uses 5 gallons of water a day. ^[1] The reason for the disparity, technology. This is why I have decided that my first project will be to build a graywater system and to reuse the water for the landscape and for the toilet. The primary resource for the design I plan to build is from Oasis.

Once I have built the greywater design from Oasis, I plan to create a wetland to further filter the water. Wetlands have been used purposefully, to filter water since the 1970s.  Numerous case studies have proven that wetlands significantly reduce many graywater contaminants including pathogens, biochemical oxygen demands, solids, nitrogen and phosphorus species and heavy metals.  

Filtering wastewater from the washing machine is necessary because it has been shown that toxins present in laundry wastewater are harming the Puget Sound.  A study, conducted by the Seattle-based nonprofit, Washington Toxics Coalition, concluded that residential washing machines send about 2,110 pounds of phthalates to wastewater treatment plants each year from household dust, about 17.5 percent of the total annual load.^[2]   

 The problem with Phthalates is that they accumulate in marine sediments and interfere with reproductive activity in marine creatures.^[2]  With experimentation, it is my hope that the wetland I create filters out these toxins. 

Eventually, I would like to reuse all of the greywater to minimize my water usage.  John Todds, developer of the Living Machine has successfully integrated ecological systems to filter wastewater to this degree. One successful example was a Living Machine  designed to treat wastewater of 80,000 gallons per day in Vermont. Here is a good article on some of the advantages and disadvantages on Living Machines.

Now that's a lot of Work.

James Prescott Joules found the specific heat of water using mechanical energy. In 1845, he used falling weights to churn water where the mechanical energy lost by the weights was equated to the heat gained by the water.^[1] From these experiments he estimated the mechanical equivalent of heat to be 838 ft•lbf of work to raise the temperature of a pound of water by one degree Fahrenheit.^[1]

Let us relate this experiment to modern day life. How much mechanical energy is needed to brew a 64 oz pot of coffee? Assuming that the tap water is 60 ◦ F the temperature needed to brew great coffee is between 190 ◦ F to 200 ◦ F. Using 190 ◦ F, the change in temperature is 130 ◦ F. The mechanical energy needed to raise the temperature of 4 pounds of water to 190 ◦ F is 435 ,760 ft•lbf .

When I took thermodynamics, I was astounded to learn the amount of work needed to heat water. However, despite the calculations I still took energy for granted. The concepts of thermodynamic did not begin to sink in until I embarked on my harvesting energy project.

Living in Seattle, I thought I would use rain water falling from the roof to harvest energy. From my calculations, during the rainiest months, the most energy harvested would be 1000 watts. My average daily usage of electricity at home is 18 kWhrs a day. The 1 kW harvested in a month is negligible.

The typical household uses 20 to 45 kWhrs a day and most people are at work for eight hours a day. However, houses can be built to optimize energy using 800 watts a day.^[2] If our houses were living organisms they would have become extinct long ago.

Nature does not waste. For example, aphids excrete an excess of glucose that they are unable to digest from plant leaves and this excess is ingested by insects and bats. The challenge for me is to learn from nature and devise technological symbiotic relationships to increase efficiency and decrease consumption. Stay tune.

1. Poynting, J.H. (2007). A Text Book of Physics. READ BOOKS. ISBN 1406773166
2. http://www.treehugger.com/files/2006/07/300whr_a_day_th_1.php