Las Vegas, NV rainwater: 4,840 gallons off a roof
Rainwater from a roof in Las Vegas, NV
4,840gallons a year
That is a 1,500 sq ft asphalt roof under Las Vegas, NV's normal 6.1 inches of rain, about 795 gallons for every inch that falls.
Las Vegas, NV's rain arrives in a wet season and stops, so storage is what matters. It takes a cistern of 2,500 gallons to carry spring rain into the dry months.
Rainfall: NOAA 1991-2020 climate normals, the North Las Vegas 4.4 Sw station (3.3 mi away). Las Vegas, NV ranks 8th wettest of the 10 cities covered in Nevada.
Month by month in Las Vegas
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 0.62 | 493 | |
| Feb | 0.89 | 707 | |
| Mar | 0.54 | 429 | |
| Apr | 0.60 | 477 | 468 |
| May | 0.19 | 151 | 519 |
| Jun | 0.09 | 72 | 531 |
| Jul | 0.68 | 540 | 458 |
| Aug | 0.41 | 326 | 491 |
| Sep | 0.67 | 533 | 459 |
| Oct | 0.54 | 429 | 475 |
| Nov | 0.34 | 270 | |
| Dec | 0.52 | 413 |
Feb is the wettest month (0.89 in, 707 gal off the roof); Jun the driest (0.09 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 Las Vegas?
Best fit: a 2,500-gallon cistern, which delivers about 3,338 gallons to the garden in a normal year (98.2% of its need).
If you set one up, ask about a rebate first: cistern-sized storage costs real money, and a buried or tall tank may need a permit. Place it where a full tank (about 8.3 lb a gallon) sits on firm, level ground.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 275 | 3,637 |
| 110 gal | 550 | 3,362 |
| 165 gal | 825 | 3,087 |
| 275 gal | 1,289 | 2,624 |
| 550 gal | 1,768 | 2,144 |
| 1,000 gal | 2,218 | 1,694 |
| 1,500 gal | 2,718 | 1,194 |
| 2,500 gal | 3,338 | 194 |
| 5,000 gal | 3,338 | 0 |
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 Nevada?
Nevada law changed after 2015 (AB138, 2017 session). The current rule has not been verified here yet; check with the Nevada Division of Water Resources before installing.
From the stale; not yet re-checked against current law, so check with your state water agency before building anything large. Source