Fairbanks, AK rainwater: 10,340 gallons off a roof
How much rain a roof in Fairbanks, AK collects
10,340gallons a year
That is a 1,500 sq ft asphalt roof under Fairbanks, AK's normal 13.0 inches of rain, about 795 gallons for every inch that falls.
Fairbanks, AK has gaps between storms long enough to drain a single barrel. Around 275 gallons of storage catches most of what is worth catching.
Rainfall: NOAA 1991-2020 climate normals, the Aurora station (2.4 mi away). Fairbanks, AK ranks 4th wettest of the 4 cities covered in Alaska.
Month by month in Fairbanks
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.57 | 453 | |
| Feb | 0.44 | 350 | |
| Mar | 0.34 | 270 | |
| Apr | 0.34 | 270 | 500 |
| May | 0.64 | 509 | 463 |
| Jun | 2.01 | 1,598 | 292 |
| Jul | 2.62 | 2,082 | 216 |
| Aug | 2.44 | 1,939 | 238 |
| Sep | 1.59 | 1,264 | 344 |
| Oct | 0.77 | 612 | 446 |
| Nov | 0.72 | 572 | |
| Dec | 0.53 | 421 |
Jul is the wettest month (2.62 in, 2,082 gal off the roof); Mar the driest (0.34 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
What size rain barrel for Fairbanks
Best fit: a 275-gallon tote or tank, which delivers about 2,126 gallons to the garden in a normal year (85.1% of its need).
If you buy one, link barrels with a short hose at the base so they fill and drain together, and check the overflow points away from the house.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 1,260 | 8,466 |
| 110 gal | 1,777 | 7,948 |
| 165 gal | 1,957 | 7,768 |
| 275 gal | 2,126 | 7,599 |
| 550 gal | 2,185 | 7,540 |
| 1,000 gal | 2,185 | 7,540 |
| 1,500 gal | 2,185 | 7,540 |
| 2,500 gal | 2,185 | 7,540 |
| 5,000 gal | 2,185 | 7,540 |
Simulated storm by storm through a normal year using the station's count of days with 0.1 in or more of rain each month.
Is rainwater collection legal in Alaska?
No rainwater harvesting regulations
From the 2015 (Pacific Northwest National Laboratory report 24347); not yet re-checked against current law, so check with your state water agency before building anything large. Source