La Plata, MD rainwater: 37,284 gallons off a roof
How much rain a roof in La Plata, MD collects
37,284gallons a year
That is a 1,500 sq ft asphalt roof under La Plata, MD's normal 46.9 inches of rain, about 795 gallons for every inch that falls.
In La Plata, 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 Port Tobacco Village 1.0 S station (4.1 mi away). La Plata, MD ranks 9th wettest of the 23 cities covered in Maryland.
Month by month in La Plata
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 3.15 | 2,504 | |
| Feb | 2.84 | 2,257 | |
| Mar | 3.85 | 3,060 | |
| Apr | 3.87 | 3,076 | 60 |
| May | 4.33 | 3,442 | 2 |
| Jun | 4.23 | 3,362 | 15 |
| Jul | 4.57 | 3,632 | |
| Aug | 4.53 | 3,600 | |
| Sep | 4.35 | 3,457 | |
| Oct | 4.09 | 3,251 | 32 |
| Nov | 3.43 | 2,726 | |
| Dec | 3.67 | 2,917 |
Jul is the wettest month (4.57 in, 3,632 gal off the roof); Feb the driest (2.84 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 La Plata
Best fit: one 55-gallon barrel, which delivers about 86 gallons to the garden in a normal year (78.4% 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 La Plata's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 86 | 36,043 |
| 110 gal | 86 | 36,043 |
| 165 gal | 86 | 36,043 |
| 275 gal | 86 | 36,043 |
| 550 gal | 86 | 36,043 |
| 1,000 gal | 86 | 36,043 |
| 1,500 gal | 86 | 36,043 |
| 2,500 gal | 86 | 36,043 |
| 5,000 gal | 86 | 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