Largo, FL rainwater: 42,617 gallons off a roof
Rainwater from a roof in Largo, FL
42,617gallons a year
That is a 1,500 sq ft asphalt roof under Largo, FL's normal 53.6 inches of rain, about 795 gallons for every inch that falls.
In Largo, 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 Petersburg Intl Ap station (5.3 mi away). Largo, FL ranks 120th wettest of the 173 cities covered in Florida.
Month by month in Largo
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.62 | 2,082 | |
| Feb | 2.38 | 1,892 | |
| Mar | 2.43 | 1,931 | |
| Apr | 2.57 | 2,043 | 222 |
| May | 2.73 | 2,170 | 202 |
| Jun | 8.86 | 7,042 | |
| Jul | 9.73 | 7,733 | |
| Aug | 8.83 | 7,018 | |
| Sep | 6.40 | 5,087 | |
| Oct | 2.49 | 1,979 | 232 |
| Nov | 1.64 | 1,303 | |
| Dec | 2.94 | 2,337 |
Jul is the wettest month (9.73 in, 7,733 gal off the roof); Nov the driest (1.64 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 Largo?
Best fit: one 55-gallon barrel, which delivers about 537 gallons to the garden in a normal year (81.9% 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 Largo's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 537 | 40,970 |
| 110 gal | 585 | 40,922 |
| 165 gal | 585 | 40,922 |
| 275 gal | 585 | 40,922 |
| 550 gal | 585 | 40,922 |
| 1,000 gal | 585 | 40,922 |
| 1,500 gal | 585 | 40,922 |
| 2,500 gal | 585 | 40,922 |
| 5,000 gal | 585 | 40,922 |
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