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SESK: Stuff Everyone Should Know · sesk.info/boat-no-discharge-zone-secure

In a No Discharge Zone, what must you do with your boat's flow-through toilet system?

Secure it so nothing can go overboard, for example padlock the valve closed.

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  1. Use it only at night
  2. Secure it so it can't discharge, like padlocking the valve ✔
  3. Add extra chemicals and keep using it

Why: In a No Discharge Zone, even treated sewage can't be discharged. The operator must secure the device, for example by padlocking or wire-tying the overboard valve closed, or closing it and removing the handle.

Huh, didn't know that: Locking the door to the toilet space is also an accepted way to secure the device.

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What did the padlock say to the valve? You're not going anywhere.
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References

Answer: Secure it so it can't discharge, like padlocking the valve. In a No Discharge Zone, even treated sewage can't be discharged. The operator must secure the device, for example by padlocking or wire-tying the overboard valve closed, or closing it and removing the handle.

  1. A Boater's Guide to the Federal Requirements for Recreational Boats (USCG) www.uscgboating.org/assets/1/AssetManager/Boaters-Guide-to-Federal-Requirements-for-Receational-Boats-20231108.pdf
    When operating a vessel in a No Discharge Zone, the operator must secure the device in a manner that prevents any discharge.
    Checked 2026-10-09.
  2. 33 CFR 159.7, Requirements for vessel operators www.ecfr.gov/current/title-33/section-159.7
    Closing the seacock and removing the handle
    Checked 2026-10-09.

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