Rainwater Harvesting in North Dakota
North Dakota (ND) receives an average of 17.8 inches of rainfall per year, placing it in the low-rainfall category among US states. The wettest month is typically Jun, and the driest is Jan. Rainwater harvesting is fully legal in North Dakota. A standard 1,500-square-foot asphalt shingle roof can collect approximately 12,934 gal per year, saving an estimated $53.50 annually at the state's average municipal water rate of 0.5 cents per gallon.
Monthly Rainfall in North Dakota
Understanding North Dakota's monthly rainfall distribution is essential for sizing your storage tank correctly. The table below shows average monthly rainfall and the resulting harvest from a 1,500-square-foot roof. North Dakota's 17.8 inches of annual rainfall is relatively low, making every drop valuable. Even in arid climates, a properly designed harvesting system provides meaningful water for drought-tolerant landscaping, container gardens, and supplemental outdoor use.
| Month | Rainfall (in) | Harvest (1,500 sq ft) |
|---|---|---|
| Jan | 0.5" | 374 gal |
| Feb | 0.5" | 374 gal |
| Mar | 0.8" | 598 gal |
| Apr | 1.2" | 897 gal |
| May | 2.4" | 1,794 gal |
| Jun | 3.0" | 2,243 gal |
| Jul | 2.8" | 2,093 gal |
| Aug | 2.2" | 1,645 gal |
| Sep | 1.6" | 1,196 gal |
| Oct | 1.2" | 897 gal |
| Nov | 0.6" | 449 gal |
| Dec | 0.5" | 374 gal |
| Total | 17.8" | 12,934 gal |
Harvest by Roof Size in North Dakota
Your actual harvest depends on how much roof area you connect to your collection system. Not every square foot of your roof needs to drain into your tank — many homeowners start by connecting just one or two downspouts covering a portion of their roof. The table below shows what different collection areas yield annually in North Dakota using an asphalt shingle roof at 80% efficiency.
| Roof Area | Annual Harvest | Rec. Tank Size | Annual Savings |
|---|---|---|---|
| 1,000 sq ft | 8,621 gal | 500 gal | $43.11 |
| 1,500 sq ft | 12,934 gal | 1,000 gal | $53.50 |
| 2,000 sq ft | 17,242 gal | 1,500 gal | $53.50 |
| 2,500 sq ft | 21,556 gal | 2,500 gal | $53.50 |
Upgrading to a metal roof (95% efficiency) boosts collection by about 19% compared to asphalt shingle. For example, a 1,500-square-foot metal roof in North Dakota captures approximately 15,358 gal per year when used for garden irrigation and toilet flushing for a household of two.
Rainwater Harvesting Laws in North Dakota
North Dakota allows rainwater collection without restrictions for residential use. The state's relatively low rainfall makes collection systems a useful supplement.
Regulation Summary for North Dakota
- Legal Status: Legal — no restrictions
- Max Collection: No limit
- Permit Required: No — for standard residential systems
- Municipal Water Rate: 0.5 cents per gallon (state average)
Popular Uses for Harvested Rainwater in North Dakota
North Dakota homeowners use harvested rainwater for a variety of purposes. The most common applications are garden irrigation, lawn watering, and toilet flushing. Each use has different water requirements and may require different levels of filtration. Explore detailed guides for the most popular uses in North Dakota:
How North Dakota Compares to Similar States
The table below compares North Dakota with five states that have similar annual rainfall patterns. All calculations use a standard 1,500-square-foot asphalt shingle roof collecting water for garden irrigation.
| State | Annual Rainfall | Legal Status | Annual Harvest | Water Cost | Annual Savings |
|---|---|---|---|---|---|
| North Dakota | 17.8" | Legal | 12,934 gal | 0.5 c/gal | $53.50 |
| Idaho | 18.9" | Legal | 11,514 gal | 0.4 c/gal | $42.80 |
| Colorado | 15.9" | restricted | 11,589 gal | 0.5 c/gal | $53.50 |
| South Dakota | 20.1" | Legal | 14,655 gal | 0.5 c/gal | $53.50 |
| Montana | 15.3" | Legal | 10,692 gal | 0.5 c/gal | $53.46 |
| New Mexico | 14.6" | Legal | 9,047 gal | 0.7 c/gal | $63.33 |
Tips for Rainwater Harvesting in North Dakota
In a low-rainfall state like North Dakota (17.8 inches per year), every gallon of harvested rainwater is especially valuable. Focus on drought-tolerant landscaping (xeriscaping) that requires minimal supplemental watering, and use harvested rainwater to support container gardens, potted plants, and select high-value plantings. A metal roof is strongly recommended to maximize collection from each rain event. Size your tank generously relative to your roof area — in North Dakota, rain events are often separated by weeks of dry weather, so you need enough storage to capture and hold the occasional heavy rain. Even modest systems provide meaningful water savings in North Dakota due to the higher-than-average water costs that accompany dry climates.
Calculate Your Specific Harvest in North Dakota
The estimates above use standardized assumptions. Use our Rainwater Harvesting Calculator to enter your exact roof area, material, household size, and intended uses for a customized analysis tailored to your property in North Dakota. You can also browse all states to compare potential across the country, or explore tank sizes and water uses for detailed information on system components and water budgeting.