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Missouri: Laws & Legal Considerations

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Rainwater harvesting: explicitly protected for both non-potable and potable use

Missouri is one of the more permissive states covered on this site, with a specific statute protecting the right to collect rainwater for either purpose.

RuleMissouri
Source water Rooftop or other catchment
Permit required No, for small-scale residential systems (typically under 100,000 gallons of storage)
Non-potable use Legal and unrestricted
Potable use Also legally protected, though appropriate treatment is still required to make it safe to drink
Underlying statute RSMo §640.648, effective August 28, 2018

Why rainwater harvesting doesn't conflict with Missouri's water rights system

Because Missouri is a riparian state rather than a prior-appropriation state, collecting rainwater on your own property doesn’t compete with anyone else’s claim to a water source the way it might in a Western prior-appropriation state. This is part of why Missouri’s rules are comparatively simple.

Where to find it: the Missouri Department of Natural Resources (dnr.mo.gov) oversees permits for larger systems.

Water rights: riparian, with a brand-new restriction on exporting water out of state

Missouri follows standard riparian reasonable-use doctrine, but a 2025 law added a genuinely new wrinkle: a specific restriction on sending Missouri’s water to other states.

ConceptHow it works in Missouri
Who holds the right Landowners touching or lying above a water source
Nature of the right Access and reasonable use, not ownership of the water itself
Water exports A law passed in 2025 restricts exporting Missouri water to other states, reflecting a broader push by the legislature to treat water as a resource worth actively protecting rather than just regulating locally

Where to find it: the Missouri Department of Natural Resources administers water resource regulation statewide.

Permitless carry since January 2017, at a distinctive age of 19

Missouri has allowed permitless concealed carry longer than most other permitless states covered on this site, and its minimum age sits between the two thresholds used elsewhere.

RequirementDetail
Standard Permitless ("constitutional") carry since January 2017
Minimum age 19 (18 with qualifying military service)
Optional Concealed Carry Permit (CCP) Available in Standard (5-year), Extended (10 or 25-year), and Lifetime versions; recognized in roughly 36 other states
Local nuance Municipalities can still require a valid CCP to open carry within city limits, even though concealed carry itself needs no permit statewide

Age 19, an outlier of its own kind

Most permitless-carry states covered on this site set the age floor at 21, and a distinct cluster (Arkansas, Idaho, Indiana, Louisiana, Mississippi, Montana, New Hampshire, North Dakota, South Carolina, South Dakota, and West Virginia as of 2026) set it at 18. Missouri’s 19-year minimum doesn’t match either group, a genuinely distinct threshold rather than the lowest one on the site.

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