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Marine Plumbing & Heads
The plumbing is where cruising boats develop their unique smells. Marine sanitation hoses, raw-water toilets, holding tanks, and seacocks all need ongoing attention — and ignoring them produces unforgettable problems. This is also the area where competent DIY pays off most directly.
What marine plumbing includes
- Heads (toilets): Manual or electric. Macerator pump. Sanitation hose.
- Holding tank: Capacity, vent line, deck pumpout fitting.
- Raw water seacocks: Engine cooling, head intake, watermaker feed, refrigeration condenser, deck washdown.
- Through-hulls and fittings: Bronze, Marelon, or stainless components.
- Fresh water: Tank, pump, accumulator, fixtures.
- Bilge plumbing: Pump discharge, manual backup, high-water alarm.
Maintenance schedule
| Item | Interval | Notes |
|---|---|---|
| Head rebuild | 2–4 years | Manual heads, cruising use |
| Sanitation hose check | Annually | Rub test for permeability |
| Sanitation hose replacement | 10–15 years | Quality marine hose |
| Seacock cycling | Monthly | Prevent seizing |
| Seacock service | Annually | Disassemble, grease |
| Through-hull replacement | 15–20 years | Bronze; sooner if galvanic issues |
| Fresh water pump | 5–8 years | Diaphragm wear |
Common costs
| Service | Common range (USD) | Notes |
|---|---|---|
| DIY head rebuild (parts) | $50–150 | Service kit |
| Pro head rebuild | $200–500 | Labour plus kit |
| Sanitation hose replacement | $200–500 | Materials |
| Hose replacement labour | $400–1,000 | Depends on access |
| New seacock installation | $250–500 each | Haul-out required |
| Composting head conversion | $2,000–4,000 | All-in |
Frequently asked questions
Head rebuild frequency?
Manual heads every 2–4 years cruising. Electric longer but harder to fix at sea.
Sanitation hose life?
10–15 years quality marine hose. Replace when rub test shows odor permeation.
Seacock maintenance?
Cycle monthly. Service annually. Replace if won't turn.
Composting heads?
Increasingly common. $2,000–4,000 all-in conversion. Eliminates hose and tank.
Head repair cost?
DIY $50–150. Pro $200–500. Full replacement $600–1,500.