St. Augustine, FL rainwater: 40,249 gallons off a roof
Rainwater from a roof in St. Augustine, FL
40,249gallons a year
That is a 1,500 sq ft asphalt roof under St. Augustine, FL's normal 50.6 inches of rain, about 795 gallons for every inch that falls.
In St. Augustine, FL 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 St Augustine Lighthouse station (1.5 mi away). St. Augustine, FL ranks 158th wettest of the 173 cities covered in Florida.
Month by month in St. Augustine
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.74 | 2,178 | |
| Feb | 2.69 | 2,138 | |
| Mar | 3.43 | 2,726 | |
| Apr | 2.93 | 2,329 | 177 |
| May | 3.66 | 2,909 | 86 |
| Jun | 6.27 | 4,983 | |
| Jul | 4.88 | 3,879 | |
| Aug | 7.18 | 5,707 | |
| Sep | 7.18 | 5,707 | |
| Oct | 4.37 | 3,473 | |
| Nov | 2.32 | 1,844 | |
| Dec | 2.99 | 2,376 |
Aug is the wettest month (7.18 in, 5,707 gal off the roof); Nov the driest (2.32 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 St. Augustine?
Best fit: one 55-gallon barrel, which delivers about 226 gallons to the garden in a normal year (85.9% 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 St. Augustine's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 226 | 38,913 |
| 110 gal | 226 | 38,913 |
| 165 gal | 226 | 38,913 |
| 275 gal | 226 | 38,913 |
| 550 gal | 226 | 38,913 |
| 1,000 gal | 226 | 38,913 |
| 1,500 gal | 226 | 38,913 |
| 2,500 gal | 226 | 38,913 |
| 5,000 gal | 226 | 38,913 |
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 Florida?
Legal. Florida approves onsite non-potable use of rainwater for landscape irrigation, vehicle washing, filling pools and fountains and, in some local jurisdictions, toilet/urinal flushing (Florida Plumbing Code). No state storage cap or registration for non-potable collection.
Checked against the current source on 2026-11-06. Source