Roswell, NM rainwater: 10,571 gallons off a roof
Rainwater from a roof in Roswell, NM
10,571gallons a year
That is a 1,500 sq ft asphalt roof under Roswell, NM's normal 13.3 inches of rain, about 795 gallons for every inch that falls.
Roswell, NM has gaps between storms long enough to drain a single barrel. Around 275 gallons of storage catches most of what is worth catching.
Rainfall: NOAA 1991-2020 climate normals, the Roswell 0.3 Ssw station (0.5 mi away). Roswell, NM ranks 9th wettest of the 19 cities covered in New Mexico.
Month by month in Roswell
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.44 | 350 | |
| Feb | 0.38 | 302 | |
| Mar | 0.56 | 445 | |
| Apr | 0.63 | 501 | 464 |
| May | 1.13 | 898 | 401 |
| Jun | 1.38 | 1,097 | 370 |
| Jul | 2.02 | 1,606 | 290 |
| Aug | 2.11 | 1,677 | 279 |
| Sep | 2.10 | 1,669 | 281 |
| Oct | 1.40 | 1,113 | 368 |
| Nov | 0.54 | 429 | |
| Dec | 0.61 | 485 |
Aug is the wettest month (2.11 in, 1,677 gal off the roof); Feb the driest (0.38 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 Roswell?
Best fit: a 275-gallon tote or tank, which delivers about 2,230 gallons to the garden in a normal year (90.9% of its need).
If you buy one, link barrels with a short hose at the base so they fill and drain together, and check the overflow points away from the house.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 1,045 | 9,151 |
| 110 gal | 1,655 | 8,541 |
| 165 gal | 1,991 | 8,205 |
| 275 gal | 2,230 | 7,966 |
| 550 gal | 2,262 | 7,934 |
| 1,000 gal | 2,262 | 7,934 |
| 1,500 gal | 2,262 | 7,934 |
| 2,500 gal | 2,262 | 7,934 |
| 5,000 gal | 2,262 | 7,934 |
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 New Mexico?
Regulated through the State Engineer Office; no specific requirements exist for outdoor uses; indoor uses must meet quality standards; 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