We installed a salt water washdown 4 years ago. I just purchased a good water pump with a pressure switch. I plumbed it into a forward through hull that was also used for 2 other items. I put a stainless hose connector with cap on deck at the bow and when needed I attach a coil type hose with a trigger nozzel on the end. When I turn on the motor (via a switch) I just point the nozzel at the chain and squirt. With the hose you can point the stream anywhere needed. Only downside is that I thought the 4 gal a minute would be great and it's only adequate and could be stronger. (Unfortunately more flow costs a lot more.) We also use the washdown for salt water washing the entire boat after a passage to get the salt off or to clean the boat before a good squall while at anchor.

All in all, it's a system that works fine and provides water for as long as I need it (we don't have a watermaker.) When we're moving and anchoring a lot I keep the hose connected and in a small Sumbrella bag tied near the cap rail.

Forgot,,,, I also have the salt water washdown pump connected to a galley spigot. Endless salt water in the galley without a foot pump. After a salt water wash we rinse with fresh.