Attwood Marine Shower Sump Pump System, 12V, Automatic, 3/4 in Outlet

Overview

The Attwood Marine Shower Sump Pump System is a 12V gray-water sump for moving water from a boat shower, sink, or tub into the proper discharge line. It combines a sump box with an automatic Attwood Sahara pump, giving the installer a contained way to manage drainage where gravity alone will not move water out of the compartment.

The range covers 500 GPH and 750 GPH configurations, with a 3/4 inch pump outlet, 36 inch wire leads, and inlet options for 3/4 inch, 1 inch, 1-1/8 inch, and 1-1/2 inch hose connections. The box uses a gasketed snap-in lid to help control overflow, and the air vent helps reduce air locks during operation.

Key features

• 12V operation fits common DC house and plumbing circuits on small and midsize boats.
• Automatic Sahara pump starts as the sump fills and removes accumulated gray water from shower, sink, or tub drains.
• Gasketed snap-in lid helps seal the box against overflow and can be removed for cleaning.
• Air vent helps prevent air locks, a common cause of poor sump drainage after the box has taken in air.
• Slotted mounting feet allow installation and removal without fighting the box in a tight locker or bilge area.
• Straight mesh filter supports quick inspection and cleaning before hair, soap residue, or debris reaches the pump.
• 3/4 inch pump outlet and multiple inlet hose sizes support connection from up to three drains when the layout allows it.
• Meets or exceeds applicable ABYC and USCG standards for this type of marine sump system.

Variants

This product is offered in two 12V configurations. The main differences are pump capacity and the sump box size associated with each part number.

Both versions use the same sump-system concept, with a gasketed lid, air vent, mesh filter, 36 inch wire leads, and a 3/4 inch pump outlet.

• 4141-4: 500 GPH. This configuration uses the standard box size, about 8-1/2 inches by 7-1/4 inches, for installations where the expected gray-water flow is moderate and space is limited.
• 4143-4: 750 GPH. This configuration uses the large box size, about 11 inches by 7-1/4 inches, for layouts with higher drainage volume or more room allocated for the sump box.

Installation and fit

Install the sump in an accessible low point near the shower or drain lines so water enters the box freely and the lid can still be removed for inspection. The multiple inlet sizes help match common hose runs from a head sink, shower drain, or galley sink, while the 3/4 inch outlet connects to the discharge hose.

Because this is a 12V pump system, wiring should be routed and protected as part of the boat's DC system. The 500 GPH version uses a 3A fuse, and the 750 GPH version uses a 5A fuse, so the final circuit protection should match the specific variant being installed.

Use cases on board

This sump is a practical match for cruisers, fishing boats, and sailboats that need controlled gray-water drainage from enclosed shower pans or sinks. It is especially useful where the sump box must sit in a bilge or locker and still remain easy to open after a weekend of soap residue, hair, and normal cabin use.

Maintenance and care

Service mainly comes down to keeping the lid, gasket, vent, and mesh filter clean. Check the box after heavy use, rinse out collected debris, and make sure the float and pump area move freely before longer trips or after the boat has been left unused.