Rainwater harvesting

Yield:

• 1 acre * 1 inch rainfall per year = 6.273e+6 in^3 / year = 27160 gallons per year
• San Diego County 55-year average (minimum, std) rainfall data = 10.26 (3.41, 4.16) inches
• 75% catchment is considered good

Usage estimate:

• 50-70% of household usage is outdoors (e.g. lawns and gardens), average American uses 100 gal/day source: CT DPH
• Average American uses 82 gal/day (29930 gal/year) source: USGS
• Average Californian uses 108 gal/day (39420 gal/year) source: National Environmental Education Foundation
• Average American drinks 44 ounces/day source: CDC

Sustainability Estimates

• # of Californians sustained off 1 acre, based on...
  • Annual Average Rainfall: 10.26 inches * 27,160 gallons/inch of rainfall = 278,661.6 gal / 39,420 gal/person/yr = 7 persons = about 2 average households
  • 97.5% Coverage (Avg - 1 StDev): 6.1 inches * 27,160 gallons/inch of rainfall = 165,676 gal / 39,420 gal/person/yr = 4.2 persons = about 1.3 average households

Detailed resources for planning a build:

• https://www.oregon.gov/bcd/documents/brochures/3660.pdf

But is it legal in California?

• https://pioneerwatertanks.com.au/is-collecting-rainwater-illegal-in-california-ca/#:~:text=The%20Rainwater%20Capture%20Act%20of%202012,-All%20of%20that&text=The%20bill%20authorizes%20residential%2C%20commercial,systems%20comply%20with%20specified%20requirements.