Rainwater Harvesting Laws for Gardens and Farms
Is it illegal to collect rainwater?
In most places, no. Rainwater collection from a roof for outdoor use is allowed or encouraged in most states. The reason people ask is that, in some western states, water law treats rain and snowmelt as part of the water supply that belongs to the public and is allocated to people with water rights. If you take water that a senior rights holder would otherwise receive downstream, there was a legal question. Several states have solved it with a small-scale exemption for household rain barrels, and others regulate larger systems.
Sources differ on how many states restrict rain collection, from a handful to none that ban it outright, because they count different kinds of limits. The National Conference of State Legislatures publishes a state-by-state summary; use it and your state statute rather than a general list.
How the rules are layered
| Layer | What it may say | Where to look |
|---|---|---|
| State water law | Whether rain can be collected, how much, for what use, and whether it creates or affects a water right. | State water agency or statute; the NCSL summary. |
| State and local plumbing code | Rules for cisterns, overflow, backflow protection and whether stored rain may connect to a building’s plumbing. | State building and plumbing code; local building department. |
| Local zoning and building codes | Setbacks and height for tanks, whether a large tank is an accessory structure, screening and permits. | City or county planning and building office. See building codes and planning and zoning. |
| Homeowners association rules | Color, placement or whether barrels are allowed in view. | HOA documents. See homeowners associations. |
| Health and mosquito rules | Lids, screens and no standing water. | County health or vector control. |
| Incentives | Rebates, tax exemptions or giveaways for rain barrels. | Your utility, city and state revenue department. |
Examples: Colorado and Texas
| State | What the rule says | Why it matters |
|---|---|---|
| Colorado | Under HB16-1005 (2016) a household may use up to two rain barrels with combined capacity of 110 gallons or less, for single-family homes and multifamily buildings of four or fewer units, with water used outdoors on the same property. Barrels must have sealable lids for mosquito control. The rule does not create a water right, and the state engineer can limit use if a senior rights holder shows harm. | Colorado is the textbook case of a state with a water-rights rule that now allows small household barrels. A garden on a larger lot or a community garden may not qualify as a single household. Confirm with the state and your city. This page has not checked changes after 2016. |
| Texas | The Texas Water Development Board encourages rainwater harvesting, and the state offers a sales tax exemption on equipment. State law (Property Code 202.007) limits the ability of homeowners associations to ban rainwater harvesting installations. | Shows how some states promote collection and protect homeowners against association bans. Confirm the current rule before you rely on it. |
These two examples are not a guide to your state. Other states have their own limits on storage size, registration, use of the water and connection to plumbing. Use the questions below to find yours.
Can a community garden collect rainwater?
Many gardens do, mostly with barrels on shed or greenhouse roofs. Questions that matter for a garden that is not a single-family home:
- Does the state rule cover the building and lot type? Some limits are written for single-family homes.
- Is there a size limit that a garden’s tank would exceed?
- Is the roof an accessory structure that may collect water for outdoor use?
- Does your lease or license allow tanks, barrels or gutters?
- Is a permit or registration required above a certain tank size?
Using rainwater safely on food
Rain collected from a roof can carry bird droppings, dust and roofing material residues. Food-safety advice from extension programs usually recommends:
- use rainwater on soil, not as a spray on the edible parts of leafy crops close to harvest;
- avoid roofs with copper, treated wood shingles or old lead flashing, which can add metals;
- keep barrels covered, with screened inlets and sealed lids, to stop mosquitoes and debris;
- wash produce before you eat it, and test the water if you plan to sell food (see irrigation water quality and food safety).
Checklist before you install
- Find your state rule: ask your state water agency or read the NCSL state summary.
- Ask your city building and planning office about permits for barrels and tanks.
- Read your lease or HOA documents.
- Check the size and number limits and the permitted use.
- Use sealable lids, mosquito screens and an overflow that drains away from buildings.
- Ask your utility about rebates for rain barrels.
- Do not connect stored rainwater to drinking-water plumbing unless the code allows it and a licensed plumber installs it.
Frequently asked questions
Is it legal to collect rainwater?
In most states, yes, at least from a roof for outdoor use. Some states set limits on size, use or registration. Check your state and city.
Is it illegal to collect rainwater in any state?
Sources differ. Historically some western states restricted it because of water rights, but most have exempted small household barrels. Check your state statute.
Why was it illegal to collect rainwater in some places?
Because in some western states, water law treats precipitation as part of the supply allocated to rights holders downstream. Many of those states now exempt small residential collection.
How many rain barrels can I have in Colorado?
Two, with combined capacity of up to 110 gallons, for a household, for outdoor use on the same property, under HB16-1005. Confirm current limits with the state.
Do I need a permit for a rain barrel?
Usually not for a small barrel, but a larger tank may need a building or plumbing permit. Ask your city.
Can an HOA ban rain barrels?
Some states limit HOA bans; Texas, for example, restricts them. Otherwise it depends on your HOA documents.
Can I use rainwater on vegetables?
Yes in most cases for watering soil. Avoid spraying edible leaves close to harvest, avoid certain roofing materials and wash produce.
Are there rebates for rain barrels?
Some utilities and cities give them. Ask yours.
Can I use a rain barrel at a community garden?
Often yes with the landowner’s approval. Check whether state limits apply to non-household sites.
Is rainwater harvesting legal in Colorado?
Yes within the limits in HB16-1005 for households. Other uses of rain run into water-rights law.
Do I need a water right to collect rain?
In most states a small roof barrel needs no water right, but a few states limit this exemption to small household systems. Check your state.
What about cisterns and big tanks?
They are more regulated: plumbing code, building permits and setbacks may apply. Ask your city and state.
Official sources
- Colorado General Assembly, HB16-1005 (residential precipitation collection) and Colorado State University Extension, Rainwater Collection in Colorado
- Texas Water Development Board, rainwater harvesting information, and Texas Property Code section 202.007
- National Conference of State Legislatures, Is Catching Rainwater Legal in Your State? (state-by-state map)
- Your state water agency and your state or local plumbing and building code
- Not checked for this page: statute text for states other than Colorado and Texas, changes after 2016 in Colorado, and local permit rules for tanks