Washington, IN rainwater: 37,523 gallons off a roof
Rainwater from a roof in Washington, IN
37,523gallons a year
That is a 1,500 sq ft asphalt roof under Washington, IN's normal 47.2 inches of rain, about 795 gallons for every inch that falls.
In Washington, IN a single barrel does most of the work. Storms come often enough that a small tank refills before it runs dry, and a bigger one would mostly sit full.
Rainfall: NOAA 1991-2020 climate normals, the Washington 1.5 Nw station (2.0 mi away). Washington, IN ranks 14th wettest of the 88 cities covered in Indiana.
Month by month in Washington
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.57 | 2,837 | |
| Feb | 2.95 | 2,345 | |
| Mar | 4.16 | 3,306 | |
| Apr | 4.75 | 3,775 | |
| May | 5.48 | 4,356 | |
| Jun | 4.69 | 3,728 | |
| Jul | 3.98 | 3,163 | 46 |
| Aug | 3.12 | 2,480 | 153 |
| Sep | 3.54 | 2,814 | 101 |
| Oct | 3.40 | 2,702 | 118 |
| Nov | 3.80 | 3,020 | |
| Dec | 3.77 | 2,996 |
May is the wettest month (5.48 in, 4,356 gal off the roof); Feb the driest (2.95 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 Washington
Best fit: one 55-gallon barrel, which delivers about 349 gallons to the garden in a normal year (83.3% of its need).
Before you buy, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Washington's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 349 | 35,944 |
| 110 gal | 349 | 35,944 |
| 165 gal | 349 | 35,944 |
| 275 gal | 349 | 35,944 |
| 550 gal | 349 | 35,944 |
| 1,000 gal | 349 | 35,944 |
| 1,500 gal | 349 | 35,944 |
| 2,500 gal | 349 | 35,944 |
| 5,000 gal | 349 | 35,944 |
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 Indiana?
No statewide rainwater harvesting regulations; check county for local incentives
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