Aberdeen, MD rainwater: 37,443 gallons off a roof
Aberdeen, MD: gallons off the roof each year
37,443gallons a year
That is a 1,500 sq ft asphalt roof under Aberdeen, MD's normal 47.1 inches of rain, about 795 gallons for every inch that falls.
In Aberdeen, 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 Aberdeen Phillips Fld station (3.1 mi away). Aberdeen, MD ranks 8th wettest of the 23 cities covered in Maryland.
Month by month in Aberdeen
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.26 | 2,591 | |
| Feb | 2.78 | 2,210 | |
| Mar | 4.10 | 3,259 | |
| Apr | 3.49 | 2,774 | 107 |
| May | 3.98 | 3,163 | 46 |
| Jun | 4.28 | 3,402 | 9 |
| Jul | 4.84 | 3,847 | |
| Aug | 4.21 | 3,346 | 17 |
| Sep | 4.84 | 3,847 | |
| Oct | 4.17 | 3,314 | 22 |
| Nov | 3.27 | 2,599 | |
| Dec | 3.89 | 3,092 |
Jul is the wettest month (4.84 in, 3,847 gal off the roof); Feb the driest (2.78 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 Aberdeen
Best fit: one 55-gallon barrel, which delivers about 155 gallons to the garden in a normal year (76.7% 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 Aberdeen's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 155 | 36,043 |
| 110 gal | 155 | 36,043 |
| 165 gal | 155 | 36,043 |
| 275 gal | 155 | 36,043 |
| 550 gal | 155 | 36,043 |
| 1,000 gal | 155 | 36,043 |
| 1,500 gal | 155 | 36,043 |
| 2,500 gal | 155 | 36,043 |
| 5,000 gal | 155 | 36,043 |
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