Tampa, FL rainwater: 39,327 gallons off a roof
Rainwater from a roof in Tampa, FL
39,327gallons a year
That is a 1,500 sq ft asphalt roof under Tampa, FL's normal 49.5 inches of rain, about 795 gallons for every inch that falls.
In Tampa, 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 Tampa Intl Ap station (3.7 mi away). Tampa, FL ranks 168th wettest of the 173 cities covered in Florida.
Month by month in Tampa
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 2.65 | 2,106 | |
| Feb | 2.62 | 2,082 | |
| Mar | 2.52 | 2,003 | |
| Apr | 2.55 | 2,027 | 224 |
| May | 2.60 | 2,066 | 218 |
| Jun | 7.37 | 5,858 | |
| Jul | 7.75 | 6,160 | |
| Aug | 9.03 | 7,177 | |
| Sep | 6.09 | 4,840 | |
| Oct | 2.34 | 1,860 | 251 |
| Nov | 1.40 | 1,113 | |
| Dec | 2.56 | 2,035 |
Aug is the wettest month (9.03 in, 7,177 gal off the roof); Nov the driest (1.40 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 Tampa?
Best fit: one 55-gallon barrel, which delivers about 581 gallons to the garden in a normal year (83.8% 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 Tampa's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 581 | 37,726 |
| 110 gal | 610 | 37,697 |
| 165 gal | 610 | 37,697 |
| 275 gal | 610 | 37,697 |
| 550 gal | 610 | 37,697 |
| 1,000 gal | 610 | 37,697 |
| 1,500 gal | 610 | 37,697 |
| 2,500 gal | 610 | 37,697 |
| 5,000 gal | 610 | 37,697 |
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