Rathdrum, ID rainwater: 35,917 gallons off a roof
Rathdrum, ID: gallons off the roof each year
35,917gallons a year
That is a 1,500 sq ft asphalt roof under Rathdrum, ID's normal 45.2 inches of rain, about 795 gallons for every inch that falls.
In Rathdrum, ID 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 Ragged Mountain station (8.2 mi away). Rathdrum, ID ranks 1st wettest of the 26 cities covered in Idaho.
Month by month in Rathdrum
| Month | Rain (in) | Off the roof (gal) | Garden shortfall (gal) |
|---|---|---|---|
| Jan | 6.53 | 5,190 | |
| Feb | 4.13 | 3,283 | |
| Mar | 4.81 | 3,823 | |
| Apr | 3.73 | 2,965 | 77 |
| May | 3.21 | 2,551 | 142 |
| Jun | 2.77 | 2,202 | 197 |
| Jul | 0.93 | 739 | 426 |
| Aug | 1.04 | 827 | 413 |
| Sep | 1.93 | 1,534 | 302 |
| Oct | 3.63 | 2,885 | 90 |
| Nov | 5.93 | 4,713 | |
| Dec | 6.55 | 5,206 |
Dec is the wettest month (6.55 in, 5,206 gal off the roof); Jul the driest (0.93 in). Garden shortfall is what a 200 sq ft vegetable bed needs beyond the rain that lands on it, April to October.
Which tank size is worth it in Rathdrum
Best fit: 2 linked 55-gallon barrels, which delivers about 1,289 gallons to the garden in a normal year (78.3% 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 Rathdrum's roof water will pass straight through it.
| Tank | Water used (gal/yr) | Spills over (gal/yr) |
|---|---|---|
| 55 gal | 986 | 32,952 |
| 110 gal | 1,289 | 32,648 |
| 165 gal | 1,317 | 32,620 |
| 275 gal | 1,317 | 32,620 |
| 550 gal | 1,317 | 32,620 |
| 1,000 gal | 1,317 | 32,620 |
| 1,500 gal | 1,317 | 32,620 |
| 2,500 gal | 1,317 | 32,620 |
| 5,000 gal | 1,317 | 32,620 |
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 Idaho?
Allowed through a legal clarification made by the Office of the Attorney General
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