The way that water is used and discarded on a boat is very different from how it is used in a house. In a boat, some water can come from, and dump into the water a boat is sitting in. These systems are complicated, due to the fact that there are different types of water depending on how it is being used. If you have a head or galley on your boat, then it is important to understand the basics of boat plumbing.
The freshwater storage tank contains water that is used for the sink and shower. You have to fill this tank yourself with city water, or drinkable well water. This clean water can be used to wash dishes, drink, or rinse and cook food. Once the water has gone down the drain it either collects in a grey water tank or gets immediately dumped overboard. Be sure to always use biodegradable soaps on your boat so that the wastewater doesn’t harm the environment. Other than that, it is completely safe to dump.
The sea-cock is a valve that sucks water from the body of water you are boating in. This water is obviously not for drinking or cooking, but it can be used to hose off the deck and flush the toilet. The sea-cock has a mesh filter that stops debris from being sucked into the plumbing system. It is extremely important to make sure the filter is cleaned out and the valve can turn easily. If the valve goes bad you could sink your boat. The bilge pump will not keep up for long. Therefore, the sea-cock and bilge pump are the two most important marine plumbing parts supplies.
Black Water Tank
Water flushed down the toilet can’t be dumped overboard. Instead, it collects in the black water tank. This tank is kept completely apart from the other plumbing systems for safety reasons. In order to dispose of black water, you must find a dock with a pumping station. Since gravity is not on your side, this involves multiple hoses and some practice.