St. Louis, MO Landscaping Rules: Rainwater Harvesting (2026)
Key Facts
- Homeowner tank limit
- 65 gallons single tank
- Interconnected tank cap
- 200 gallons total
- Eligible dwellings
- One- and two-family attached homes only
- Installer required otherwise
- Licensed Master Drainlayer
- Max penalty
- $500 fine or 90 days jail
Summary
St. Louis homeowners in one- and two-family dwellings can install a rainwater collection tank up to 65 gallons, or interconnected tanks totaling 200 gallons, without hiring a licensed Master Drainlayer.
Rainwater collected from exterior downspouts to a collection container and the overflow from such container piped to a discharge point shall be installed as licensed and permitted by this Code by a Licensed Master Drainlayer. Exception: ... B)For one and two family attached residential dwellings the homeowner is authorized to install a single tank of not more than sixty-five (65) gallons or a series of interconnected tanks, none of which is larger than sixty-five (65) gallons accumulating not more than two hundred (200) gallons.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 11).
Full Breakdown
St. Louis's Plumbing Code (2021 Uniform Plumbing Code as locally amended) treats a rainwater catchment system as licensed plumbing work. A Licensed Master Drainlayer must install the collection container and its overflow piping for most properties. The one exception: owners of one- and two-family attached dwellings can self-install a single downspout tank up to 65 gallons, or several interconnected tanks none larger than 65 gallons each, capped at 200 gallons total. Anything bigger, any overflow piped to a public sewer or waterway, and any water drawn off for irrigation, fixtures, or fire suppression still requires a licensed Master Plumber, Drainlayer, Sprinkler Fitter, or Pipefitter, and potable make-up water added to the tank needs backflow protection.
Violations & Fines
Violating the Plumbing Code's rainwater-tank licensing rules, installing beyond the 65-gallon homeowner exemption without a Master Drainlayer, draws up to a $500 fine, 90 days in jail, or both; each day is a separate offense.
Frequently Asked Questions
Do I need a permit to install a rain barrel in St. Louis?
What if I want a bigger rainwater tank?
Sources & Official References
Other rules in St. Louis
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