A non-partisan, neutral perspective supporting diversity in the color of water

Monday, April 19, 2010

Greywater Returns on Investments?

The Oregon Water Thorn alluded to a presentation at the Oregon Onsite Wastewater Association annual meeting where the cost savings in a homeowner's wastewater billing was discussed.  No facts were shared, and the link to the conference is broken on their site.  But I did locate an article where greywater is aggressively being promoted in the City of Guelph, Ontario, Canada.

According to this press release from the American Water Works Association, Guelph is conducting a feasibility study on recycling graywater in homes. "Each reuse system is expected to reduce the water used by a family of two by approximately 32,850 L (8,678 gallons) per year and to reduce water and wastewater utility costs by approximately Can$73 (US$73) annually per household".... and "For a new home, purchasing and installing a reuse system typically runs Can$3,500 (US$3,479), says Galliher, while costs to retrofit an existing home with a reuse system can be roughly Can$4,000 (US$3,992) or more depending on the home’s floor plan and other factors".

Let's return to the topic of site evaluation and permitting that has been discussed by the Oregon Graywater Advisory Committee. There was some talk of requiring a site evaluation costing somewhere between $500 and $1,000, and some talk about a DEQ permit (costs not discussed, but safe to assume somewhere around $100 based on existing permitting fees for "other" wastewater permits). So it would take about eight years to see a return on the initial investment for site evaluation and permitting. The return on investment for the greywater treatment system?  Check out the comments that accompany this article.

Assuming that 10% of Oregon homes try greywater reuse (recall that California estimates about 15% of the homes in that state participate) and couple the approximately 140,000 homes with the $73 yearly savings leads to about $10,000,000 per year out of the pockets of the wastewater treatment plants. On the basis of this simple analysis, it comes as no surprise that the folks in the wastewater business are not so fond of greywater reuse!

But the cost savings are not limited to those who are "on the grid".  This transplanted Oregonian describes the problem of greywater overloading his septic system in Patagonia, Argentina. He contacted unnamed greywater experts in Oregon for technical assistance (they have to remain unnamed like the Greywater Gangsters as greywater reuse is illegal in Oregon until the DEQ finishes the laborious task of writing the rules). The ultimate solution to exceeding the capacity of an aging septic system? Disconnect the greywater system from the septic system.  Note to DEQ - check out this clever solution to filtration using, of all things, recycled wine bottles! Recall that the Santa Cruz Sentinel also reported "Graywater systems not only decrease the burden on septic tanks $500 per pumping and leach fields, they also serve to slow the contamination of groundwater and aquifers". (Note, these articles have not been peer-reviewed for accuracy).

The Greywater Gadget of the Week does not focus on equipment, but rather a process, known as ECOTEL. ECOTEL’s metamorphoses into a more green, inclusive, and interactive certification, involving owners, guests, employees and the community.  Oregon had a chance at one of these types of facilities in the Metolius basin in Central Oregon until Governor Kulongoski decided that Oregon's legendary land use laws, and the reliance on counties to work through the process, did not "protect" this area and created the first Area of Critical Concern in Oregon through legislative mandate. ECOTEL, along with our new friends and neighbors, Just Water Savers USA, provide interesting fodder for business opportunities in budget war-torn Oregon.

Oregon needs to embrace these green businesses and processes for eco-tourism rather than fight them. Let's make it easy for Oregonians to save nearly 1.2 billion gallons of water per year by not having expensive and burdensome site evaluation and permit fees.


  1. Hi Todd,

    Permitting is an issue, and hopefully the state will take a reasoned risk management approach. It would appear to me the treatment benefits of use of dripperlines at sub surface level (on soil, below mulch) has not been understood by quite a few states in here in the US.

    The canadian example is interesting, as for $4,000 (approx) they are saving 8,000 gallons per year (toilet flushing) whereas $2,000 (approx) will save about 12,000 gallons per year (2 people) if used instead of potable water on the garden.

    Here is an example of ROI in the Santa Barbara area:

    GRAY Barrel pumping unit $585.00
    IrriGRAY Dripperline Kit $425.00

    Dripperline Installation $-
    retro fit or new home $850.00


    Graywater potential
    Number of residents 3
    Water use per person per day 60
    Graywater % of total water use 70%
    Total graywater per day 126
    Total graywater per month 3780

    Potable water irrigation saving
    Assumed graywater dripperline efficiency 80%
    Assumed potable water efficiency (deep watering) 50%
    Irrigation efficiency increase factor 1.6
    Equivalent potable water saved (per month) 6048

    Gallons per HCF 748.5
    Total domestic water use (inside house) 5400
    Equivalent HCF 7.214428858
    Water Supply (after 4 HCF) charge, per HCF $4.76
    Service sewer rate, per HCF $2.09
    Potable water saving 6048
    Equivalent HCF 8.080160321
    Water & Sewer saving $55.35

    Running costs
    Assumed flow rate (1/2 full filter) 6
    Total water pumped, per month 3780
    Run time, per month 10.5
    Watts (660w pump) 6930
    Cost per Kilowatt Hour $0.11
    Monthly electricity cost $0.76

    Economic Summary years 5
    Pump replacement ($300 each 5 years) 0
    Assumed operating months per year 9
    Installation $1,860.00
    Running costs (electricity) $34.30
    Total cost $1,894.30
    Water & Sewer Saving $2,490.71
    Net Benefit $596.41

    Economic Summary years 10
    Pump replacement ($300 each 5 years) $300
    Assumed operating months per year 9
    Installation $1,860.00
    Running costs (electricity) $68.61
    Total cost $1,928.61
    Water & Sewer Saving $4,981.42
    Net Benefit $3,052.81

  2. Hi Todd,

    Great blog but I can't figure out how to contact you other than commenting...

    We are the owners of an Aqua2use Greywater System from Matala. We thought the system was so great that we decided to become a distributor. The Aqua2use Greywater System would be a great greywater gadget to include in your blog!

    You can find info here: http://waterwisegroup.com/

  3. Paul and Jenni:

    Paul - your comment is so good that I will repeat as a posting.

    Jenni - Aqua2use will be next week's Greywater Gadget of the Week. Thanks for reading and sharing your product!

  4. Todd:
    Thanks that's great. We're trying to get the word out because we think it's such a great and easy system. If you have any questions, feel free to contact me at jenni@waterwisegroup.com. And if you have any other ideas on ways to let water conscious people be aware of the system, I'd love to hear your thoughts.
    Thanks and Happy Earth Day!

  5. I do apologize for the lack of specificity my post - I had hoped to have actual dollars and cents but the copy of the slideshow presentation I got is so stinking tiny that I can hardly read it. I think, if my eyes are reliable, they are suggesting per capita savings of about $80 per year in avoided drinking water and sewer treatment costs. It is not clear if they are using the operational costs from the treatment plants or if they are using homeowner rates avoided. That doesn't work in my area because my utility charges a flat base fee for a certain amount of water, which I don't typically exceed, so I wouldn't avoid any costs by using greywater. It would take the altruistic sort in that situation to help the local utility avoid treatment costs....some have called me that in the past...