Jabsco Par-Max HD4 12V 4-GPM 40-PSI Water Pump

The Jabsco Par-Max HD4 12V Water Pump (part Q401J-115S-3A) supplies about 4 gallons per minute with a 40 psi shutoff. Four gallons a minute covers a typical midsize boat with a galley, a head sink, and a shower. The lower pressure setting is a sensible choice for older boats with original hose and fittings.

Its bypass module lets the pump run smoothly at low flow rather than chattering on and off, so a slow trickle at the sink does not cause constant cycling. The co-molded diaphragm and EPDM check valves are made for long service in potable water. A cast aluminum lower housing supports the heavy duty motor.

Mount it on its vibration-dampening feet on a solid surface to keep motor hum out of the cabin. The pump self-primes, so it can sit above the tank in a dry, reachable spot. Keep an inlet strainer ahead of it and clean the screen at the start of each season. The 60 psi HD4 and other freshwater pumps are in our fresh water and washdown pumps.

• 12V, about 4 GPM at 40 psi
• Suits midsize boats with several outlets
• Bypass module for low-flow smoothness
• Vibration-dampening feet