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Thursday, April 22, 2010

More on Greywater and ROIs

Paul James from Just Water Savers USA provided this comment to an earlier post.  Not knowing if the comments get read with regularity, I decided to repost his comment given that it shows another way to look at the returns on investments (ROI) and greywater:

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

GRAY Barrel pumping unit $585.00
IrriGRAY Dripperline Kit $425.00

Dripperline Installation cost to 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 gallons
Total graywater per month 3,780 gallons

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) 6,048 gallons

Gallons per Hundred Cubic Feet (HCF) 748.5
Total domestic water use (inside house) 5,400 gallons
Equivalent HCF 7.21
Water Supply (after 4 HCF) charge, per HCF $4.76
Service sewer rate, per HCF $2.09
Potable water saving 6,048 gallons
Equivalent HCF 8.08
Water & Sewer saving $55.35 

Running costs
Assumed flow rate (1/2 full filter) 6
Total water pumped, per month 3,780 gallons
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

Note that Paul does not include costs for site evaluation or permitting, which up to this point have been estimated to be between $500 to $1,000 (one time) and $100 (unknown if this might be one time or recurring in Oregon).  On the basis of Paul's analysis, making greywater "pay" is very dependent on the site evaluation and permitting fees.

Water conservation activities associated with greywater will more than likely cut into the budgets of water and wastewater utilities thus requiring increases in the water rates as less water is used and treated as outlined in this article published by the Circle of Blue WaterNews.

Other communities such as Guelph, Ontario (see previous posting) and various entities in Australia "sweeten" the water conservation pot by providing subsidies for the installation of greywater reuse equipment.  If Oregon is truly concerned about the suitability of individual sites for greywater reuse, perhaps the site evaluation fees could be rebated, much like the "rebate" received for returned beverage bottles or energy efficient appliances.

Greywater reuse in Oregon is going to cost money - either on the front end in terms of encouraging individuals to invest in greywater reuse through waiving of permit fees or rebating site evaluation studies, or on the back end through decreased revenues to water and wastewater utilities. Given how many tens of millions of dollars have been invested in salmon restoration through the Oregon Plan, or through Oregon trying to get out of the "top ten" list of states with impaired waters as identified by the Clean Water Act by either reducing diversions or reducing discharges, Oregon's investment in greywater reuse will probably pay off in the long term.  It will all come down to how Oregon invests in spreading the message.

Water agencies should be communicating to customers that yes, rates went up in the short term, but it is far less than if we had to build new facilities for a new water source. I don’t think agencies have been good in communicating. I think it’s a failure across the board to engage people...” Heather Cooley, Pacific Institute

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