1. An accumulator, or expansion tank, is a slightly pressurized metal or plastic tank with a water-filled bladder inside. If the water pressure drops—for instance, if a faucet is turned on momentarily—the water in the bladder flows back into the pipes. This keeps the pump from starting up immediately. If your system suffers from water hammer or knocking, an accumulator will cure it. We decided not to install one because, like many modern pumps, the 4.75 gpm Whale I used is extremely quiet, and because replacing the entire water system pretty much guaranteed there wouldn’t be any leaks.
2. Many slip-domiciled boats have a shore-supply connection that allows a marina hose to be plugged into the ship’s water system. This is often accomplished via a garden hose fitting linked to the tank, but that’s not a good idea; letting water pressurized at 100 psi into a system that’s not designed to cope with more than 40 psi is asking for trouble. If you must do this, buy and install an inline pressure regulator. I decided I could live without plumbed-in shore water.
3. I debated whether to install an inline water filter, but so far I have not done so. The tanks are fairly new and the water does not taste bad. If I do eventually install a charcoal filter, it will go in the feed line to the two manual pumps.
4. I decided not to fit a salt-water pump at the galley. If I decide to install one in the future, I’ll plumb it to a through-hull and seacock, which it will share with a deck wash pump.