Marine Systems Guide
Modern Yacht Plumbing Systems
A modern yacht uses several separate water systems, each with its own pumps, hoses, fittings, tanks, valves, strainers, fixtures, and service requirements. Freshwater, bilge, sanitation, raw-water, washdown, livewell, and watermaker systems all serve different jobs onboard.
Use this page with the infographic below to understand how water moves through a vessel, identify the major components, and shop the correct marine pumps and plumbing parts for service, repair, or refit work.
System Diagram
Modern Yacht Water & Plumbing Layout
The diagram shows how major water systems route through a typical modern yacht, including freshwater supply, bilge discharge, black-water plumbing, raw-water intakes, washdown supply, livewell circulation, and watermaker desalination.
On mobile, swipe the diagram left or right to view the full system layout.
How To Use This Page
Match Each System to the Correct Marine Products
Yacht plumbing parts are not interchangeable just because they look similar. A freshwater pump, bilge pump, raw-water pump, washdown pump, livewell pump, and macerator pump all have different performance requirements. Use the sections below to match the system in the diagram to the right product group.
System Breakdown
Modern Yacht Plumbing Systems
Each color-coded system below matches the infographic and links to matching collections or safe site search pages.
Freshwater System
The freshwater system supplies clean pressurized water to the galley, head sink, shower, aft shower station, deck shower, and onboard fixtures.
- Freshwater tank
- Pressure pump
- Filter or purifier
- Accumulator tank
- Water heater
- Faucets, taps, and showers
Bilge System
The bilge system removes unwanted water from the lowest areas of the hull and discharges it overboard through dedicated hose and through-hull outlets.
- Bilge pump
- Float switch
- Bilge hose
- Check valve
- Through-hull discharge
- High-water alarm
Sanitation / Black-Water System
The sanitation system manages waste from the marine toilet through sanitation hose, valves, holding tanks, macerators, vents, and deck pump-out fittings.
- Marine toilet
- Sanitation hose
- Holding tank
- Y-valve or diverter
- Macerator pump
- Deck pump-out fitting
Raw-Water System
The raw-water system pulls seawater through the hull to supply engine cooling, generators, air conditioning, watermakers, and other raw-water-fed equipment.
- Raw-water inlet
- Through-hull fitting
- Seacock
- Sea strainer
- Raw-water pump
- Cooling hose
Washdown System
The washdown system provides pressurized water for cleaning decks, rinsing anchors, washing down cockpits, and supplying aft or rear shower stations.
- Washdown pump
- Deck wash fitting
- Hose reel
- Spray nozzle
- Rear shower station
- Washdown hose
Livewell System
The livewell system circulates and refreshes water in bait tanks or livewells using supply pumps, aerators, drains, overflow lines, and fittings.
- Livewell pump
- Aerator pump
- Livewell tank
- Drain fittings
- Overflow line
- Circulation hose
Watermaker / Desalination System
The watermaker system converts seawater into freshwater using an intake, strainer, prefilters, high-pressure pump, membrane, freshwater output, and brine discharge.
- Seawater intake
- Prefilters
- High-pressure pump
- Membrane unit
- Freshwater output
- Brine discharge
Core Components
Common Plumbing Parts Used Across Multiple Systems
Many yacht plumbing systems rely on similar supporting components. Before replacing a part, confirm hose diameter, voltage, pressure rating, flow direction, thread type, material, and installation location.
Fitment Notes
How to Choose the Right Pump or Plumbing Part
Yacht plumbing parts must match the system, material, size, pressure, flow, voltage, and service environment. Use the notes below before ordering replacement parts.
Match the System
Freshwater, bilge, raw-water, washdown, livewell, sanitation, and watermaker systems all require different components. Do not substitute by appearance alone.
Confirm Voltage & Capacity
Check 12V or 24V, flow rate, pressure rating, duty cycle, amperage draw, inlet size, outlet size, and pump type before replacing a pump.
Measure Hose & Fittings
Confirm inside diameter, outside diameter, thread type, barb size, hose rating, clamp size, and whether the hose is for freshwater, bilge, sanitation, or raw water.
Respect Through-Hulls
Raw-water inlets, discharges, seacocks, and through-hulls are safety-critical. Use marine-rated components and inspect them regularly.
Shop Marine Pumps & Plumbing Systems
Browse the main pumps and plumbing categories or use search links to find specialized parts shown in the Modern Yacht Plumbing Systems diagram.