Manually pumping a single glassful of water is easy. Pumping water to wash the dinner dishes becomes a real chore. A pressure water system provides the "water on tap" convenience of big city life. Several pressure water options are available ranging from single faucet pumps to complicated systems allowing full hot and cold running water. As with most things on boats, the wisest choice is always the simplest system that gets the job done.

Dedicated Pump/Faucet Combo

Nothing beats the dedicated pump/faucet combination for simplicity. This is the best solution for a boat that has only one sink or when water is wanted in an isolated location. The biggest disadvantage to a dedicated pump system is that it works only for cold water.

A dedicated system has two parts. One is the special faucet in which the standard water valve has been replaced with an electric switch. The other part is the actual pump motor. In service, they are connected by wires so that when the switch is turned "on," the pump runs.

The faucet is installed behind or beside the sink so that water from the spigot goes into the sink. Two holes in the counter top are usually necessary: one for the water; and the other for the electrical wires. Some faucets use one large hole for both. Screws hold the base plate in place. Most faucets have a rubber gasket to keep water splashed on the counter top from dripping into the counter beneath the sink.

Pumps that come with dedicated systems are designed for in- line installation in plastic tubing. They are not self-priming, so must be installed below the bottom of the water tank. Cut the tubing close to the tank and install the pump using stainless-steel hose clamps on the inlet and outlet barbs.

Wire the positive (+) wire from a fuse or circuit breaker to the switch on the faucet. From the switch it goes to the pump. The negative (-) wire goes directly from the pump to the boat's ground bus.

Multi-Tap System

A multi-tap system uses a much larger pump to deliver pressure water to faucets at the galley sink and at vanity sinks in the head compartments. Fresh water may also be delivered to an ice maker or shower from the pressure water system. It may even have a tap in the cockpit for freshwater washdown.

The pressure pump is the heart of this system. It is essentially an electric motor that operates a small diaphragm pump through a crank arrangement. A pressure switch turns the motor "on" and "off" to match water demand. In service, the pump keeps pressure on the entire system to each water tap. When that pressure drops, the switch starts the pump running until the pressure on the system has been built up again.

Because pressure is always on the system, flexible plastic tubing is not recommended. Leaks at connections due to loose hose clamps are all too common with plastic tubing. It's much better to plumb a pressure system with plastic piping like that used in home construction.

A shutoff valve at the water tank allows routine maintenance of the pressure pump without draining the tank. The pump can be located almost anywhere in the boat, although it is normally near the water tank. Choose a spot with enough room around it to allow for repairing the pump. Sooner or later, the diaphragm will need replacement.

Electric power for the pump motor should come directly from a dedicated switch on the boat's main 12-volt distribution panel. This allows manual control of the pump motor during repairs or when the boat is unattended. Be sure the switch and associated fuse are in the positive (+) side of the circuit. Connect the feed wires to the appropriate terminals on the pump assembly. The electrical pressure switch is normally wired internally and does not require special connections.

Water can be plumbed directly to the various taps from the pump. However, this approach requires the pump motor to cycle every time somebody gets the first drop of water. This cycling can be rapid and annoying, especially at night when other members of the crew are trying to sleep. Installing an accumulator tank in the output of the pump smoothes out surges in the system and ends rapid pump cycling.

Connecting an accumulator tank is simple. Put a "T" in the pump outlet pipe. The tank installs on one leg of the "T" while water to the boat is fed out the other leg. (Some tanks have built-in "T" fittings.) An accumulator tank works by compressing air trapped in the tank when water is pumped into the system. Compressed air keeps pressure on the system during periods of small demand, effectively preventing the pressure switch from cycling the pump motor.

Although not required, taste and odor filters go a long way toward removing the "tanky" taste of boat water. Filters intended for household service are satisfactory if they are made of non- corrosive plastic. A "crud" filter intended to remove tank sediment and other large objects should be installed just past the accumulator tank. A taste and odor filter should be installed at the galley sink faucet.

Ordinary household faucets can be used on boats. Chromed brass or all-plastic fixtures work well in the marine environment. Do not purchase a standard "hot and cold" water fixture if the boat will have only cold pressure water. Accidentally opening the "hot" water tap will send water rushing, but not out of the spigot. Instead, it will rush out of the hot water inlet and into the cabinet beneath the sink.

Safety Warning

Sediment, taste and odor filters do not purify water. They are intended only to improve the quality of safe drinking water from municipal water systems. These filters do not remove harmful bacteria that cause disease. Special bacteriostatic filters are available for boats voyaging to areas with questionable water supplies.

Adding Hot Water

Adding pressurized hot water is done after the original installation of a pressure pump. Simply "T" off the cold water system just past the accumulator tank to feed water to the hot water heater. Plastic piping should always be used to deliver hot water around the boat. Vinyl hose softens when it carries hot water. Preventing leaks in a hot water system made of vinyl tubing is the Devil's own game. Heat softens the vinyl and that allows it to creep off hose barbs even if tightly clamped.

It's a good idea to install a check valve on the inlet to the hot water tank. This valve prevents hot water from flowing back into the cold water system. The "outlet" of the check valve goes to the "inlet" of the tank.

Existing Manual Pumps

Foot or hand pumps can be left in place even after installation of a pressure water system. However, check valves should be installed in the lines feeding these pumps. The check valves will prevent the electric pump from sucking air into the system backwards through the manual pumps.

Choosing Pipe For Boat Plumbing

Potable (drinking) water should always be plumbed through FDA approved plastic tubing or hard plastic plumbing. Non-approved hoses can leach chemicals into the water. This problem is especially acute on boats that often remain idle for days or weeks at a time. Water sitting in a non-approved hose can take on unpleasant odors or flavors as well as chemicals.

Approved hoses and other plumbing materials are not hard to find. Most chandleries carry FDA approved vinyl tubing. Accept- able plastic piping is available through most hardware stores and lumber yards. Look for the FDA approval mark stamped on the pipe itself or on the original factory container in which the plastic tubing was shipped.

Vinyl Tubing

FDA approved vinyl tubing comes in sizes ranging from 3/8- to 1 1/4-inches in diameter. It is used in conjunction with plastic hose barb fittings that allow the tubing to connect to pumps, spigots and other fixtures. Stainless steel hose clamps must always be used on barb connections for security. Vinyl tubing is suitable for pressurized systems up to 15 p.s.i. It should never be connected to dockside water without a pressure reducer at the inlet to the boat. Vinyl is not suggested for carrying hot water because it softens and deforms when heated.

CPVC Plastic Pipe

CPVC (chlorinated polyvinyl chloride) pipe is a rigid material, normally light buff in color, and available in 1/2- and 3/4-inch sizes. It stays rigid even when carrying hot water because of the chemical nature of the thermoplastic material. This is the standard plastic piping for use in home construction. A wide variety of "T," "L" and other end fittings are available. Suitable for cold or hot water up to 180 degrees at 100 p.s.i.

CPVC pipe joints are made by welding the pipe with a solvent and glue. The pipe is cut to length and any burrs removed with a knife or sandpaper. Cutting can be done with a hacksaw or a pipe cutter fitted with a plastic pipe cutting wheel. Both the end of the pipe and the inside of the fitting are then cleaned with a special cleaning solvent. Glue is then wiped on the outside of the pipe and on the inside walls of the fitting. The fitting is pushed onto the pipe with a slight twisting motion until it bottoms. The glue sets up in less than an hour, but allowed it to cure for 24 hours before applying water to the system.

CPVC pipe is not the first choice for boat plumbing. It is relatively rigid and does not conform well to the curves of the hull or other confined spaces. A large number of elbow fittings are often required to create the necessary bends. Each fitting is a potential source of leaks. Also, being somewhat rigid, CPVC pipe may be subject to vibration fatigue failures.

PB Plastic Pipe

PB (polybutylene) pipe is normally grey in color and flexible enough to bend through gentle curves. This latter characteristic makes it an excellent choice where straight runs are few. It can be "snaked" through confined spaces. Available in 1/2-inch and 3/4-inch sizes. PB pipe cannot be solvent welded. All fittings are "push-on" style that use compression and O-rings to seal watertight. It is suitable for hot water to 180 degrees and cold water delivery to 100 psi.

Joints are more expensive with PB piping than any other type of boat plumbing. The increased cost is explained by the complexity of the fitting which contain an "O" ring and a compression cone. The pipe is pushed into the fitting until it bottoms and then the nut tightened hand tight. Use of a pipe wrench is not recommended as excess force may damage the fitting or the pipe.

Copper Tubing

Copper tubing (usually 3/8-inch diameter) is often used for both hot and cold water lines on boats. This tubing comes in coils which are unrolled to the desired length. Because it is flexible, few elbows or other joints are necessary. The tubing can be bent around gentle curves to reach almost any part of the boat. Compression fittings allow joining copper tubing to conventional faucets and other plumbing fixtures.

Compression fittings work, as their name implies, by compressing a small brass ring around the copper tubing. The soft brass mashes down and makes a mechanically strong and watertight joint. Soldered connections are not advised on boats because of the extreme danger of fire when using a propane blowtorch.