Hagerstown, MD rainwater: 34,288 gallons off a roof
How much rain a roof in Hagerstown, MD collects
34,288gallons a year
That is a 1,500 sq ft asphalt roof under Hagerstown, MD's normal 43.1 inches of rain, about 795 gallons for every inch that falls.
In Hagerstown, 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 Hagerstown 1.0 Ene station (1.2 mi away). Hagerstown, MD ranks 21st wettest of the 23 cities covered in Maryland.
Month by month in Hagerstown
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.28 | 2,607 | |
| Feb | 2.58 | 2,051 | |
| Mar | 3.77 | 2,996 | |
| Apr | 3.67 | 2,917 | 85 |
| May | 4.49 | 3,569 | |
| Jun | 3.70 | 2,941 | 81 |
| Jul | 3.61 | 2,869 | 92 |
| Aug | 3.64 | 2,893 | 89 |
| Sep | 4.40 | 3,497 | |
| Oct | 3.50 | 2,782 | 106 |
| Nov | 3.04 | 2,416 | |
| Dec | 3.46 | 2,750 |
May is the wettest month (4.49 in, 3,569 gal off the roof); Feb the driest (2.58 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
Barrel or cistern in Hagerstown?
Best fit: one 55-gallon barrel, which delivers about 362 gallons to the garden in a normal year (80.0% of its need).
If you buy one, a 55-gallon barrel with a downspout diverter is the whole job. Check that the overflow points away from your foundation, because most of Hagerstown's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 362 | 32,861 |
| 110 gal | 362 | 32,861 |
| 165 gal | 362 | 32,861 |
| 275 gal | 362 | 32,861 |
| 550 gal | 362 | 32,861 |
| 1,000 gal | 362 | 32,861 |
| 1,500 gal | 362 | 32,861 |
| 2,500 gal | 362 | 32,861 |
| 5,000 gal | 362 | 32,861 |
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