Pressure Pump/Accumulator Tank Systems
What Is a Pressure Pump/Accumulator Tank System?
If you've ever been aboard a boat or inside an RV and noticed the water pump cycling on and off every time someone opens a faucet — or felt that annoying pulsing surge of water pressure in the shower — a pressure pump accumulator tank system is the fix. These compact but highly effective devices work in tandem with your onboard freshwater pump to deliver smooth, consistent water pressure throughout your plumbing system.
At the heart of every accumulator tank is an internal air bladder. When the pump pressurizes the system, water fills the tank and compresses the air bladder. Once the pump shuts off, the pressurized air in the bladder continues to push water out at steady pressure, so the pump doesn't need to cycle back on for minor draws like filling a glass or a quick hand wash. The result is quieter operation, more even water delivery, and significantly reduced wear on your pump motor.
Why Accumulator Tanks Matter for Boats and RVs
Both marine and RV freshwater systems rely on pressure switch-controlled pumps that activate whenever line pressure drops below a set threshold. Without an accumulator tank, every small demand for water — even just cracking open a faucet — triggers the pump. This rapid on/off cycling, sometimes called "short cycling," accelerates wear on the pump's motor and pressure switch, and creates water hammer shock that can stress fittings, gaskets, and seals over time.
Adding an accumulator tank addresses these issues simultaneously. It extends the life of the pump by reducing on/off pulsation, lowers battery consumption (critical on anchor or off-grid), and stabilizes temperature delivery — especially noticeable with on-demand water heaters and showers, where pressure fluctuations cause frustrating hot-and-cold swings.
Temperature extremes and changes in altitude can affect accumulator pressure and performance, so it's good practice to check the pre-charge pressure seasonally or any time the system seems to be underperforming. A standard tire pressure gauge is all you need.
Choosing the Right System
When selecting an accumulator tank, the most important factor is matching the tank's pre-charge pressure to your pump's cut-in (turn-on) pressure. Most marine and RV pumps have a cut-in pressure in the 20–40 psi range. As a general rule, the larger the tank capacity you can fit in your available space, the more effective it will be at reducing pump cycling and prolonging pump life. Accumulator tanks are designed for pressure switch-controlled pumps; if your vessel uses a variable-speed pump, verify compatibility before installing.
Top Brands in Pressure Pump/Accumulator Tank Systems
Jabsco is one of the most recognized names in marine and RV freshwater systems. Their accumulator tanks feature an internal bladder construction in a compact, impact-resistant plastic housing that can be mounted in virtually any orientation. Jabsco tanks are designed specifically to complement their own pressure pump lineup — including the well-known PAR-MATE series — and integrate easily into both new builds and existing systems with convenient snap-fit hose fittings.
Groco brings a heavier-duty, marine-grade perspective to accumulator tanks with their PST series. Groco's steel-construction tanks use a rubber bladder that fully separates the air charge from the water, and their design can be matched precisely to the pump cut-on pressure to prevent waterlogging. Available in a wide range of sizes and rated for both fresh and saltwater use, Groco PST tanks are a popular choice for larger vessels where higher drawdown capacity is needed.
B&B Detailer Products rounds out this category with additional options for complete pressure pump and accumulator system setups, offering solutions for owners looking to build out or upgrade their onboard water systems.