Cumberland, MD rainwater: 31,172 gallons off a roof
Rainwater from a roof in Cumberland, MD
31,172gallons a year
That is a 1,500 sq ft asphalt roof under Cumberland, MD's normal 39.2 inches of rain, about 795 gallons for every inch that falls.
In Cumberland, MD 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 Cumberland 2 station (0.7 mi away). Cumberland, MD ranks 23rd wettest of the 23 cities covered in Maryland.
Month by month in Cumberland
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.79 | 2,218 | |
| Feb | 2.38 | 1,892 | |
| Mar | 3.42 | 2,718 | |
| Apr | 3.41 | 2,710 | 117 |
| May | 4.22 | 3,354 | 16 |
| Jun | 3.87 | 3,076 | 60 |
| Jul | 3.73 | 2,965 | 77 |
| Aug | 3.40 | 2,702 | 118 |
| Sep | 3.55 | 2,822 | 100 |
| Oct | 2.82 | 2,241 | 191 |
| Nov | 2.58 | 2,051 | |
| Dec | 3.05 | 2,424 |
May is the wettest month (4.22 in, 3,354 gal off the roof); Feb the driest (2.38 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 Cumberland
Best fit: one 55-gallon barrel, which delivers about 526 gallons to the garden in a normal year (77.4% 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 Cumberland's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 526 | 29,431 |
| 110 gal | 526 | 29,431 |
| 165 gal | 526 | 29,431 |
| 275 gal | 526 | 29,431 |
| 550 gal | 526 | 29,431 |
| 1,000 gal | 526 | 29,431 |
| 1,500 gal | 526 | 29,431 |
| 2,500 gal | 526 | 29,431 |
| 5,000 gal | 526 | 29,431 |
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 Maryland?
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