Pump-outs, MSDs and Clean Boating on the Water

Boats with a permanent head (toilet) must manage sewage lawfully. Under Clean Water Act section 312, vessels with installed toilets that operate on U.S. navigable waters need an operable U.S. Coast Guard–certified marine sanitation device (MSD). Portable toilets ("porta-potties") are not installed toilets, so the MSD carriage rule does not apply to them—but untreated waste from a portable toilet still may not be dumped in U.S. waters out to three miles offshore (EPA; Discover Boating).

This guide covers MSD Types I, II and III, when and why to use a pump-out, No Discharge Zones (NDZs) at a high level from EPA (and the operator rules EPA and the Coast Guard describe), and how to find pump-out stations on our per-state places hubs (for example Alaska pump-outs) and state pages. For invasive-species clean/drain/dry, see clean boating and invasive species. Pump-out before winter lay-up and again at spring commissioning are also in winterizing your boat and spring commissioning.

Rules are federal plus local. Always confirm where you boat with State Rules and the EPA NDZ list for your waters—we do not invent station lists or NDZ maps.

What an MSD is (and who needs one)

EPA defines an MSD as equipment installed on a vessel to receive, retain, treat or discharge sewage (and any process that treats that sewage). Section 312 requires an operable, Coast Guard–certified MSD when the vessel:

  1. has an installed toilet, and
  2. operates on U.S. navigable waters (including the three-mile territorial seas).

Discover Boating adds the same practical rule: you are not required to carry a head, but if you install one, it must connect to a USCG-certified Type I, II or III MSD.

Type I, II and III (EPA / Coast Guard)

The Coast Guard groups certified MSDs into three types. Performance numbers below are from EPA's MSD page (and EPA's recreational boaters' sewage guide).

Type I — flow-through treatment (≤ 65 feet)

  • Suitable for vessels 65 feet or less.
  • Typically maceration plus disinfection (often chlorine tablets; some units generate bactericide from salt water with electrodes).
  • Treated effluent must have no visible floating solids and a fecal coliform count not greater than 1,000 per 100 mL.

Type II — flow-through treatment (any length)

  • May be installed on vessels of any length.
  • Often a biological system (aeration so bacteria break down waste), then disinfection (chlorine, UV or similar). Some Type II units also use maceration and disinfection.
  • Treated effluent must have fecal coliform not greater than 200 per 100 mL and total suspended solids not greater than 150 mg/L.

Type III — holding tank (any length)

  • Typically a holding tank that stores sewage until it can be pumped out ashore or, where lawful, discharged at sea beyond three miles from shore.
  • Designed to prevent overboard discharge of treated or untreated sewage (or waste derived from sewage). No separate "treatment performance" standard like Type I/II.

Many recreational boats use a Type III tank with a deck pump-out fitting. If a holding tank has a "Y" valve that can send waste overboard, federal rules require that valve to be secured closed while you operate in U.S. waters where untreated discharge is prohibited (Discover Boating; EPA NDZ compliance guidance). Acceptable securing methods include removing the handle, a padlock or a non-releasable wire-tie.

Where untreated (and treated) discharge is banned

EPA and Discover Boating summarize the baseline:

  • Untreated sewage (including from a portable toilet or a Type III tank) may not be discharged in U.S. waters within three miles of shore, or in an NDZ.
  • To discharge within three miles, sewage must be treated with a certified Type I or Type II MSD—or retained in a Type III tank for shore pump-out (or for lawful discharge beyond three miles where that is allowed and you are outside an NDZ).
  • Any sewage—treated or untreated—is prohibited in:
    • designated No Discharge Zones;
    • certain freshwater lakes, reservoirs and impoundments whose inlets/outlets are too shallow for vessels with installed toilets to enter and leave;
    • rivers that do not support interstate traffic by vessels subject to section 312 (see 40 CFR Part 140 as cited by EPA).

Discover Boating's clean-boating tips put it simply: never discharge sewage within three miles of shore; use harbor pump-out stations and shore-side facilities; empty a porta-potty at a dump station or bathroom ashore.

No Discharge Zones (high level)

An NDZ is an area where both treated and untreated vessel sewage discharges are prohibited (EPA). Inside an NDZ you must keep sewage onboard for shore pump-out or for discharge beyond three miles from shore only where that is still lawful outside the NDZ.

EPA lists NDZs by state (with Federal Register links and maps) at its No-Discharge Zones (NDZs) by State page. Designation types include protecting habitats where pump-outs are available (CWA 312(f)(3)), special habitats or species (312(f)(4)(A)), and drinking-water intake zones (312(f)(4)(B)). We do not republish NDZ maps or invent boundaries—use EPA's state tables and your state agency.

Securing the MSD in an NDZ

EPA (citing 33 CFR 159.7) describes how operators must secure devices in waters where discharge is prohibited:

Type I or II (flow-through) — one of:

  • close the seacock and remove the handle;
  • padlock the seacock closed;
  • use a non-releasable wire-tie to hold the seacock closed; or
  • lock the door to the space enclosing the toilets.

Type III (holding tank) — one of:

  • close overboard-discharge valves and remove the handle;
  • padlock those valves closed; or
  • hold them closed with a non-releasable wire-tie.

When and why to use a pump-out

Use a shore (or mobile) pump-out to empty a Type III holding tank when:

  • you boat inside the three-mile coastal band, on inland waters, or in an NDZ (treated discharge may also be banned there);
  • the tank is approaching capacity—EPA's recreational guide says to empty regularly so you are not forced into an unlawful discharge;
  • you are about to haul out for winter (Discover Boating: pump out before winter storage; our winterizing checklist includes pumping out and antifreezing the heads);
  • you are commissioning in spring—Discover Boating's spring list includes pumping out and sanitizing the holding tank (spring commissioning).

EPA's recreational boaters' guide also notes practical habits: confirm the facility is open before you go; rinse/flush the pump-out line after the tank is empty when the station instructions say to; maintain the MSD and plumbing; prefer rapidly dissolving toilet paper to limit clogs.

When tied to a dock, Discover Boating recommends using onshore restrooms so the tank fills more slowly on day trips.

How to find pump-out stations on MyNextBoat.ai

We list pump-out / dump stations from public open data—primarily OpenStreetMap tags (amenity=sanitary_dump_station with boat use, related waterway/seamark tags, marinas tagged for dump stations) plus some state Clean Vessel Act / agency inventories where we could integrate them. Coverage is incomplete and volunteer-driven for OSM rows; many states have no official statewide pump-out file in our dataset yet. Blank fields mean unknown, not "none." Attribution: © OpenStreetMap contributors (ODbL) where rows are OSM-derived; see Sources and methods for OpenStreetMap and agency attribution and limits.

Do not treat our list as complete. Cross-check with the marina, your state environmental or boating agency, and EPA's pump-out / Clean Vessel Act resources before you rely on a stop.

Browse by state hub

Every state places hub that has pump-out rows links them as Pump-out stations:

Rows that include coordinates link to an OpenStreetMap map pin. Where a source URL exists, the table cites it (OSM or the agency inventory).

Clean boating habits that go with pump-outs

Beyond sewage, Discover Boating's clean-boating practices also cover: oil-absorbent pads in the bilge, containing maintenance waste, proper hazardous-waste disposal ashore, stowing trash, and reducing graywater impacts. Pair pump-out discipline with Clean, Drain, Dry so you are not moving invasives while you move the boat between waters.

Seasonal plumbing and head care: maintenance calendar by season.

When to call a pro

  • The MSD will not pass a Vessel Safety Check or is unlabeled / uncertified when an installed head requires one.
  • The Y-valve, seacock or deck fitting is stuck, leaking or corroded.
  • The holding tank or hoses smell strongly through the boat even after a pump-out and rinse—hoses may need replacement (Discover Boating notes better hose can cut odors).
  • You are unsure whether your waters are inside an NDZ or which device securing method fits your plumbing—ask a marina tech or check EPA's state NDZ tables and the Coast Guard / state boating office.

Sources

Related tools