Water Usage Statistics

From GreenGarageWiki

Our goal with water usage was to use water at a fraction of a level of a traditional commercial office building. We did this in a variety of ways, from selection of efficient plumbing fixtures to reduction of use of city water through the use of cisterns. Our data is below.

Our 2 cisterns, prior to placement. The larger cistern, 1,400 gallons, is under our parking lot, and the smaller, 500 gallons, is on top of our 3-season room. Both are fed with water coming from our roof.

Measurement Decisions

The statistics come from our monthly City of Detroit water bills.
Unit of measure = gallons (water dept measures in cu, where 1cu = 100 cubic feet = 728 gallons)
'Usage Per Person' is calculated based on the number of people that are in Businesses-in-Residence at the beginning of each month, plus the number of volunteers and paid contractors that work more than 2 days a week.

Sources of Water

Our water comes from the City of Detroit Water and Sewerage Department, which gets its water from the Detroit River and Lake Huron.
Water for outside use comes from 2 cisterns, one on top of our roof, and one under our parking lot. Together, they collect about 2,000 gallons of water.

Uses of Water

4 Toilets (@ 1.28 gal/flush)
5 Sinks
- 3 Bathroom (0.5 gal/min + automated)
- 1 Kitchen
- 1 Mop-basin
2 Dishwasher (4 gal / load)
1 Shower (2.5 gal/min shower head)
Coffee / Drinking
Outdoor watering. We harvest the water that we use for outdoor watering in 2 cisterns (1,700 gallons total) and only use city water when the other water is exhausted. Our goal is to use no city water for outdoor use.

Water Usage Charts

Green Garage Monthly Water Usage - April 2012 - April 2013

April 2013 showed a slight downturn in usage from 3 previous months
Please note that in October we had a valve that didn't close on one of the toilets, causing it to run all weekend, which caused the spike in water usage. A repair was made and the problem has not recurred.
Average 35-40 guests every Friday

Monthly Water Usage Comparison Chart - April 2012 - April 2013

We averaged 33 gallons per person in the month of April. We have 69 people in the Green Garage.
Studies show water usage per person per month in office space is between 300-500 gallons. sources: US Department of Energy Federal Office Building Water Efficiency Report and North Carolina Division of Water Quality