Yacht pumps: bilge, fresh water, waste
Choosing, fitting and maintaining bilge pumps, fresh water pressure pumps and waste pumps.
The pumps on a boat serve three separate circuits that must never be mixed. The bilge pump removes water collecting in the bottom of the hull, the fresh water pump supplies the domestic system under pressure, and the waste pump serves the heads and the holding tank. Each system has different hygiene and material requirements. The choice starts with working out the output needed for the particular boat and the system voltage (usually 12 V or 24 V DC).
Bilge pumps divide into diaphragm types (self-priming, tolerant of running dry and of small debris) and submersible centrifugal ones (high output, but they need to be primed and cannot run dry). The catalogue output is quoted at zero head — the real flow drops with the length and rise of the hose and with friction. So choose a pump with a margin and allow for the loss over the delivery head. The standard is an electric pump with a float switch plus a hand pump for emergencies, independent of the power supply.
The bilge system must be properly vented and have an anti-siphon loop, so that seawater cannot run back into the hull by gravity when the boat heels. The bilge outlet is placed above the waterline, and a vented loop with a valve is fitted in the hose. Mount the float switch at the lowest point of the bilge, cleaned of dirt, so that debris cannot jam it. It is worth adding a cycle counter or a bilge alarm warning of unusually frequent pump operation.
The fresh water system is built round a pressure (diaphragm) pump with a pressure switch that maintains pressure in the pipework. For comfort and to reduce the number of pump cycles, an accumulator tank is used, plus a filter on the suction side protecting the pump's valves. Match the output to the number of outlets — on a small yacht typically about 10–12 l (3.2 US gal)/min. The pipework and fittings must be approved for drinking water, and the tank has to be disinfected periodically.
Waste pumps serve the heads and the holding tank. You find manual heads with a diaphragm pump and electric ones with a macerator. The whole installation must comply with the rules on discharge — in many waters discharge overboard is prohibited and the tank has to be emptied at a pump-out station. Use hoses with low odour permeability and anti-siphon loops, to prevent flooding and water getting in. The seacocks must work and be accessible.
Maintaining diaphragm pumps mainly means replacing diaphragms, non-return valves and seals from the maker's service kits. Protect fresh water pumps with a filter and bleed them after filling the tank. For the winter, drain every circuit without fail or blow it through and fill it with non-toxic antifreeze for water systems, because frozen water splits pump and valve bodies. Winterise the heads as the instructions say, flushing the system with winter fluid.
When sizing pump wiring, calculate the cross-section for the voltage drop and the starting current, and protect every circuit with a fuse matched to the pump. Use crimp connectors with heat-shrink sleeving and run the cables above bilge level. Established makers such as Jabsco, Whale and Vetus publish output selection tables and installation diagrams. Keep repair kits on board and remember that an independent hand bilge pump is a safety item, not a luxury.
Material prices — products and options
Indicative prices in EUR (incl. VAT), as at July 2026. Products widely available in Europe; prices depend on the shop, the output and the voltage version. The links go to example shops that ship across the EU. Dollar amounts are converted at 1 EUR = 1.1622 USD (ECB, 7 September 2026) and rounded — treat them as a rough guide, not a price in a US shop. Imperial values in brackets are conversions of the metric figure.
Electric bilge pumps
- Rule — automatic bilge pump 500–1100 GPH
submersible with an electronic sensor, 12 V€40–95 (≈$46–110) - Whale — Gulper IC (automatic, with a filter)
diaphragm, electronic control + non-return valve, 12/24 V€300–500 (≈$349–581) - Johnson / Jabsco / Vetus — submersible pump 600–2000 GPH
popular submersible pumps, with and without automatic switching€40–130 (≈$46–151)
Hand bilge pumps (emergency)
- Whale — Gusher Urchin
diaphragm hand pump, deck or bulkhead mounting€120–260 (≈$139–302) - Whale — Gusher 30
large hand pump up to 111 l (29.3 US gal)/min, bulkhead mounted€400–800 (≈$465–930)
Float switches and bilge alarms
- Rule — A-Matic Plus (float) 40 A
independent float switch for a non-automatic pump€45–60 (≈$52–70) - Bilge alarm (independent sensor)
warns of water in the bilge independently of the pump€25–70 (≈$29–81)
Fresh water pressure pumps
- SHURFLO — Pressure Water Pump (marine-grade)
with a pressure switch, stainless components€80–160 (≈$93–186) - SHURFLO — Aqua King II
higher output for systems with several outlets€120–200 (≈$139–232) - Jabsco / Johnson / Marco — pressure pump
alternative diaphragm pumps with automatic pressure control€70–180 (≈$81–209)
Heads and holding tank
- Jabsco — manual / electric heads
marine toilet with spare parts and service kits€90–450 (≈$105–523) - Jabsco — holding tank discharge pump
for emptying the holding tank€400–460 (≈$465–535)
Hoses, clamps, anti-siphon loops and filters
- Approved hoses + stainless worm-drive clamps
bilge/water hoses of the right diameter, A4 clamps€2–15 (≈$2–17) - Anti-siphon loop (vented loop)
stops water being siphoned into the system below the waterline€20–45 (≈$23–52) - Suction filter / bilge strainer
protects the pump from blocking€10–35 (≈$12–41)
Electrical accessories and service kits
- Fuses, cable, crimp connectors
pump supply matched to the 12/24 V installation€10–40 (≈$12–46) - Service kits (diaphragms, non-return valves)
consumable parts for diaphragm pumps€15–60 (≈$17–70)
Price sources: svb24.com, compass24.com, the makers' sites (Rule, Whale, Jabsco, Johnson, SHURFLO). Prices depend on the output and the version.