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The Marine Head — Complete Guide

The marine head is the piece of equipment that causes more frustration, more odor, and more arguments among cruising sailors than any other system on the boat. It's also one of the most straightforward to understand and maintain — once you know how it works. This page covers the full picture: manual vs. electric, system components, holding tanks, macerators, legal requirements, and the best products on the market.

The #1 rule of a marine head: Nothing goes in it that hasn't been eaten first. Marine heads are not trash cans. Wet wipes (even "flushable" ones), paper towels, feminine products, cotton balls, and anything else that doesn't dissolve in seawater will clog the system, foul the joker valve, and cause you misery. Marine-grade toilet paper only — or use less of it than you think you need.

Manual vs. Electric Marine Head

Characteristic Manual Head Electric Head
Cost $150–$500 $400–$1,200+
Water usage per flush 1–3 quarts (operator-controlled) 1–3 pints (metered)
Power requirement None 3–10A at 12V per flush; wiring required
Reliability offshore Excellent — no electrical failure possible Good — motors, switches, and solenoids can fail
Ease of use Requires learning proper pump technique Push-button; intuitive for guests
Clog resistance Vulnerable — joker valve and hose can clog Electric macerator reduces clog risk
Serviceability Excellent — simple parts; rebuild kits cheap Moderate — motor and electronics require more skill
Noise Quiet Motor and macerator are audible throughout the boat
Freezing / cold climate Winterize by pumping out; simpler More components to flush and protect
Best for Offshore cruising, self-sufficient passagemaking, boats without good electrical systems, budget builds Liveaboards, marina-based cruising, boats with guests, strong house banks
Offshore recommendation: The overwhelming consensus in the bluewater cruising community is to use a manual head. If the motor on an electric head fails at sea, you have a serious problem. A manual head's rebuild kit lives in the spares box and can be installed at sea with basic tools. Many experienced cruisers carry a manual head as a backup even on boats with electric primaries.

System Components

Manual Head Components

Pump Body & Piston

The heart of the manual head — a double-action piston pump that simultaneously draws seawater into the bowl (intake stroke) and pushes waste out to the holding tank (discharge stroke). The pump handle connects directly to the piston. Worn piston seals are the most common failure — they cause the pump to feel "spongy" and lose priming. Replace seals every 2–3 years as preventive maintenance.

Joker Valve (Duckbill Valve)

A one-way rubber check valve shaped like a duck's bill — it opens under pressure to allow waste to pass, then collapses shut to prevent back-flow, odor, and siphoning. The single most important maintenance item on a manual head. When the joker valve fails (stiffens from age, tears, or gets fouled with debris), the head will back-siphon and smell terrible. Replace every 12–24 months as preventive maintenance regardless of condition. Cost: $8–$20. Failure to replace is the #1 cause of head odor and backflow.

Intake Through-Hull & Seacock

Seawater enters the head through a dedicated through-hull fitting. This seacock must be operational — it is a critical safety valve. A failed-open head intake seacock allows the sea to enter the boat through a clogged hose. Service annually: exercise (open/close) the seacock several times to keep it from seizing; grease the cone or ball per manufacturer spec. Replace if it cannot be fully closed or shows corrosion.

Discharge Hose & Fittings

Connects the pump discharge to the holding tank or Y-valve. Marine sanitation hose (MSH) is odor-resistant; standard PVC hose is not adequate — it becomes permeated with odor compounds within a season. Use Raritan, Trident, or other USCG-approved sanitation hose. Replace hose every 5–10 years or when it becomes stiff, discolored, or odorous regardless of apparent condition. Smooth-bore hose (vs. corrugated) reduces debris accumulation.

Y-Valve (3-Way Valve)

A seacock-like valve that directs waste flow either to the holding tank or overboard (where legally permitted). In No Discharge Zones, the Y-valve overboard port must be secured closed — padlocked or wire-tied — to prevent accidental discharge. The Y-valve handle should be clearly labeled. Replace if it cannot be fully turned or shows bypass leakage.

Electric Head Additional Components

Macerator Motor

An electric motor driving a rotating cutter that grinds waste into a fine slurry before it enters the discharge hose. The macerator eliminates most solid clogs, uses less water per flush (because solids are reduced), and reduces holding tank odor. Macerators can burn out if run dry — never run an electric head repeatedly when the bowl is empty. Impeller blades wear and may need replacement every few years.

Control Switch & Solenoid Valve

Electric heads typically use a rocker or push-button switch controlling a solenoid valve that meters flush water. These are common failure points — carry a spare switch. Solenoid valves can stick open (flooding the bowl) or closed (no flush water). Most are inexpensive and replaceable in 30 minutes.

Fresh Water vs. Raw Water Flush

Some electric heads (VacuFlush, Tecma) flush with pressurized fresh water from the boat's water system — using only 1–3 pints per flush. This eliminates the raw water intake and associated seacock and odor from organic matter in raw seawater that dies in the hoses. Fresh water flush is the standard on quality liveaboard systems but requires a pressurized water system and consumes water tank capacity.

All Heads — Shared Components

Holding Tank

The required receptacle for all waste in US navigable waters. See the Holding Tank section below for full coverage.

Tank Vent

A critical and commonly neglected component. The holding tank must be vented to prevent pressure build-up. Vent lines must run to a fitting on the hull above the waterline — never below. The vent should be routed to the outside of the boat (not into the cabin). A vent filter (activated carbon) can dramatically reduce dock odor from the vent line.

Sanitation Hose

All hoses in the sanitation system should be USCG-approved sanitation hose — either smooth-bore for new installations or corrugated where flexibility is required. Sanitation hose is the most overlooked odor source on older boats. If a boat has original hose from the 1980s–90s, it is permeated and should be replaced entirely even if it's not leaking.

Holding Tanks

Sizing Your Holding Tank

  • General rule: 10 gallons per person per week of typical cruising use is a practical starting point
  • A couple (2 people) on a weekend cruise needs ~5–8 gallons minimum; for a week of anchoring without pump-out access, 15–20 gallons is comfortable
  • Most production sailboats came with 10–20 gallon original tanks — adequate for coastal use with regular pump-outs; undersized for extended cruising
  • Tank size is ultimately constrained by available space in the boat — measure your locker carefully before ordering a custom tank
  • Consider a second tank rather than one oversized tank — two 15-gallon tanks fit where one 30-gallon tank won't
  • Rigid fiberglass or polyethylene tanks are preferred; flexible bladder tanks work but are harder to clean and can develop odor problems over time
  • The Boat Galley — What Size Holding Tank?

Tank Materials

  • Polyethylene (HDPE) — most common; odor-resistant; available in custom sizes from tank fabricators; good long-term option
  • Fiberglass — durable; can be glassed directly into the boat; difficult to clean interior surfaces; used in original installations on many older boats
  • Stainless steel — premium option; expensive; does not absorb odors; heavy
  • Flexible bladder tanks — convenient for odd spaces; brands include Nauta, Ronco, and Sterncraft; odor permeation is a long-term concern

Pump-Out Best Practices

  • Pump out before the tank is full — a tank that overflows is significantly harder and messier to deal with
  • After pumping out, add 1–2 gallons of fresh water to rinse the tank, then pump that out too
  • Add holding tank treatment immediately after pump-out — before the tank is used again
  • Pump-out stations are at most marinas and many fuel docks; EPA Pump-Out Station Locator
  • BoatUS membership includes discounts at some pump-out facilities and maintains a pump-out station directory
  • Many pump-out facilities are free in No Discharge Zones — funded by Clean Vessel Act grants

Odor Control

  • The most effective odor control is a properly installed and maintained system — tight hose connections, a functional joker valve, and odor-resistant hose throughout. No additive compensates for a failing system.
  • K-O Marine — No-Flex Digestor; enzymatic holding tank treatment that breaks down waste and reduces odor
  • Unique Marine Digest-It — bacteria/enzyme tank treatment; highly rated in the cruising community
  • EcoStrong Marine Holding Tank Treatment
  • Vent line carbon filter — an activated carbon filter on the tank vent hose dramatically reduces dock odor; replace filter element annually or when odor breaks through
  • Avoid formaldehyde-based treatments — they kill the bacteria that break down waste, defeating the purpose, and damage pump diaphragms
  • Run raw water flush briefly after each use — keeps solids moving and reduces buildup on hose walls
  • Practical Sailor — Solutions for a Stinky Holding Tank

When a Macerator Pump is Needed

  • A macerator pump grinds waste into a fine slurry — it is distinct from a macerator head (though electric macerating heads have one built in)
  • Required when: the holding tank is below the waterline and cannot gravity-drain to the pump-out deck fitting; when you need to empty the tank overboard (where legally permitted offshore); when the pump-out hose from tank to deck fitting is long or runs at an upward angle
  • Offshore overboard discharge: In US waters beyond 3 nautical miles (12 miles in some areas), a macerator can pump macerated waste overboard through a seacock — legal only when outside restricted waters with Y-valve in overboard position
  • Important: Never run a macerator pump dry — it will burn out the impeller immediately; always ensure waste is in the tank before activating
  • Leading macerator pumps: Jabsco, Rule, SHURflo

Federal Law & No Discharge Zones

Federal law (Clean Water Act Section 312): Any vessel with an installed toilet operating on US navigable waters must have a USCG-certified Marine Sanitation Device (MSD). The three types are described below. Failure to comply can result in fines up to $2,000 per violation.

MSD Types

  • Type I MSD — flow-through treatment device; treats waste to <1,000 fecal coliform bacteria per 100ml with no visible floating solids; approved for discharge in most US waters outside NDZs; not commonly used on sailboats under 65 ft
  • Type II MSD — higher treatment standard (<200 fecal coliform per 100ml); used on larger vessels and offshore; not common on sailboats under 50 ft
  • Type III MSD — a holding tank that stores all waste and does not discharge at all; the standard on most recreational sailboats; waste must be emptied at a pump-out facility or discharged overboard outside restricted waters where permitted

No Discharge Zones (NDZs)

  • NDZs prohibit discharge of any sewage — treated or untreated — within the zone; Type I, II, and III MSDs are all prohibited from discharging inside an NDZ
  • When in an NDZ, Y-valves leading to overboard discharge must be physically secured closed — padlocked or non-releasable wire tie
  • Notable NDZs include: Puget Sound (entire Sound), Lake Champlain, Florida Keys National Marine Sanctuary, many Great Lakes areas, and portions of Long Island Sound and Chesapeake Bay
  • EPA — No Discharge Zone Map — find NDZs by state
  • Puget Sound is an NDZ — any boat sailing in Puget Sound must have a functioning holding tank and secured overboard discharge

Offshore Discharge Rules

  • Outside US navigable waters (generally 3 nm from shore), MARPOL Annex IV governs sewage discharge
  • Beyond 3 nautical miles: comminuted and disinfected sewage (Type I equivalent) may be discharged
  • Beyond 12 nautical miles: untreated sewage may be discharged if the vessel is underway at >4 knots
  • Some coastal states have stricter rules than the federal baseline — check state regulations
  • BoatUS Foundation — Sewage Rules

Winterizing the Head System

  • Close the intake seacock; pump all water out of the bowl and hoses with dry pump strokes
  • Pour 1–2 quarts of non-toxic RV/marine antifreeze (propylene glycol — pink antifreeze) into the bowl; pump through the system until pink antifreeze appears at the through-hull discharge or holding tank inlet
  • For electric heads: flush the macerator chamber with antifreeze; consult manufacturer instructions
  • Empty and thoroughly flush the holding tank before winterizing — frozen waste in a tank is unpleasant in spring
  • Leave the seacock in the closed position all winter

Top Marine Head Products

Manual Heads

Groco Model K

Made in USA Practical Sailor Top Pick Manual

Price: ~$400–$500

Bronze pump body; the highest-quality manual head made. One of only two US manufacturers remaining. Practical Sailor's top pick in manual head testing. Heavy, durable, repairable indefinitely. Standard on quality offshore boats. Parts available directly from GROCO (Annapolis, MD).

groco.com | Defender

Raritan PH II (PHII)

Made in USA Most Popular Manual Manual

Price: ~$275–$350

The most widely installed manual head on American sailboats. Made in the USA (Raritan, NJ). Rebuild kits are inexpensive and widely available. The Raritan PHII has been the workhorse of cruising sailboats for decades — if you own an American production sailboat from the 1970s–2000s, there's a good chance you have one already. Excellent parts support; rebuild videos on YouTube.

raritaneng.com | Defender | Fisheries Supply

Raritan Crown Head II

Made in USA Manual

Price: ~$175–$225

Raritan's entry-level manual head; plastic construction; lighter and less expensive than the PHII. Good for smaller boats or as a secondary head. Same rebuild kit availability as all Raritan products.

raritaneng.com

Jabsco Twist 'n' Lock

Manual

Price: ~$200–$280

Tool-free bowl removal via the twist-and-lock mounting system — makes cleaning and servicing much easier. Compact design; good for smaller head compartments. Strong build quality; good clog resistance for a manual head.

jabscopump.com | Defender

Lavac Popular / Premium

Vacuum-Assisted Manual

Price: ~$350–$550

Unique vacuum-flush design — closing the lid creates a seal; a single diaphragm pump is the only moving part; creates vacuum that draws waste out and pulls flush water in. Extremely simple; minimal clog risk; used extensively on offshore racing boats. The diaphragm pump can be any manual pump already on the boat. No joker valve.

marinesan.com — Lavac

Electric Heads

Raritan Marine Elegance

Made in USA Best Electric Electric

Price: ~$650–$900

Practical Sailor's top-rated electric head. Porcelain bowl; powerful macerator; quiet operation; excellent flush performance. Fresh water or raw water flush models available. The standard of quality in electric marine heads. Made in the USA.

raritaneng.com — Electric Heads

Raritan SeaEra

Made in USA Best Value Electric Electric

Price: ~$450–$600

Practical Sailor's "best budget" electric head pick. Same American manufacturing as the Marine Elegance at a lower price point. Good flush performance; solid build quality; good parts support. The right choice for sailors who want electric convenience without the Marine Elegance price.

raritaneng.com

Dometic MasterFlush / SilentFlush

Electric

Price: ~$600–$1,100

Premium European electric head with very quiet operation; low water consumption; fresh or raw water flush. Popular on Beneteau, Jeanneau, and other European production boats as original equipment. Good quality; parts available through Dometic dealers.

dometic.com — Marine Sanitation

VacuFlush (Dometic)

Electric Vacuum

Price: ~$800–$1,400 (system)

Uses fresh water and a vacuum generator to flush — only 1 pint per flush; completely odor-free (no raw seawater in the lines); no through-hull required for intake. The premium liveaboard system. Requires a separate vacuum generator unit. Extremely clean; very popular on larger liveaboard boats.

marinesan.com — VacuFlush | dometic.com

Alternative / Composting Heads

Nature's Head / Air Head (Composting)

Composting Made in USA

Price: ~$900–$1,100

No holding tank required; no through-hulls; no pump-out stations needed. Separates liquid from solid waste; solids compost with a peat or coir medium; liquids collected in a separate bottle. Zero odor when maintained properly. Requires a 12V fan for ventilation (~0.25A). Ideal for boats without adequate holding tank space or cruisers in remote areas without pump-out access. Made in USA.

natureshead.net | airheadtoilet.com

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