Griffith, IN rainwater: 32,468 gallons off a roof
Griffith, IN: gallons off the roof each year
32,468gallons a year
That is a 1,500 sq ft asphalt roof under Griffith, IN's normal 40.9 inches of rain, about 795 gallons for every inch that falls.
In Griffith, 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 Dyer 1.0 Wnw station (5.4 mi away). Griffith, IN ranks 62nd wettest of the 88 cities covered in Indiana.
Month by month in Griffith
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.36 | 1,876 | |
| Feb | 2.11 | 1,677 | |
| Mar | 2.46 | 1,955 | |
| Apr | 3.87 | 3,076 | 60 |
| May | 4.37 | 3,473 | |
| Jun | 4.83 | 3,839 | |
| Jul | 4.39 | 3,489 | |
| Aug | 4.16 | 3,306 | 24 |
| Sep | 3.41 | 2,710 | 117 |
| Oct | 3.66 | 2,909 | 86 |
| Nov | 2.95 | 2,345 | |
| Dec | 2.28 | 1,812 |
Jun is the wettest month (4.83 in, 3,839 gal off the roof); Feb the driest (2.11 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
Which tank size is worth it in Griffith
Best fit: one 55-gallon barrel, which delivers about 225 gallons to the garden in a normal year (78.5% of its need).
If you set one up, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Griffith's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 225 | 31,088 |
| 110 gal | 225 | 31,088 |
| 165 gal | 225 | 31,088 |
| 275 gal | 225 | 31,088 |
| 550 gal | 225 | 31,088 |
| 1,000 gal | 225 | 31,088 |
| 1,500 gal | 225 | 31,088 |
| 2,500 gal | 225 | 31,088 |
| 5,000 gal | 225 | 31,088 |
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