Anyone who has ever had a cottage or cabin that got it's water from a well knows that,  just opening the faucet doesn't mean anything worth using is going to come out, if anything at all comes out. Wells need to be monitored for contamination, pumps need to be serviced, and you have to add your own disinfectant to prevent bacteria. Even though the water source, to fill the water tank,  for most boaters is city water, the last two items still can not be ignored.

Understanding how to operate and maintain a marine water system becomes much easier if you understand what it takes to install one and what the procedure is for getting it ready for use and for testing it. This section covers installation of the pump and what to do to maintain the system after the system is put into service.

SHURflo's Marine Duty Potable Water Pumps were developed to endure the harsh marine environment. The patented Tri-a-fram" design delivers smooth, consistent flow at all ranges of operation, while drawing low current. The balanced diaphragm design incorporates precision ball bearings for long life. Each motor is equipped with an integral thermal breaker and are all U/L Marine listed. All Marine duty pumps have sealed switches and are finished with a baked-on polyurethane coating to inhibit corrosion. Marine duty potable water pumps are enclosed to prevent incidental moisture from entering; however, they are not intended for environments where splashed water is present. When installed correctly, Marine Duty Potable Water Pumps provide years of quiet operation.

The pump can be at the same level or below the  water tank. It may be positioned above the water  tank if needed, as it is capable of a 6 ft. [1.8m]  vertical prime. Horizontal inlet tubing will allow  priming to 30 ft. [9m].
Consider a dry location that allows easy access if  maintenance is required. The pump should not be  located in an area of less than one cubic foot  unless adequate ventilation is provided. Excessive  heat may trigger the integral thermal breaker and  interrupt operation. When the temperature drops the  breaker will automatically reset and start operation.
The pump may be mounted in any position. If  mounting the pump vertically, the pump head should  be in the down position so that water will not enter  the motor.
Use #8 stainless steel hardware to fasten the pump.  Choose a solid surface (thick plywood) that will  not amplify pump operation. The mounting feet are  intended to isolate the pump from the mounting  surface; over tightening, flattening, or use of  oversized screws will reduce the ability to isolate  vibration/noise.

The pump should be on a dedicated (individual)  circuit protected by the specified "slow blow" fuse indicated on the motor label.
A U/L approved marine duty (ignition protected) switch rated at or above 15 amps is recommended, and must interrupt current flow on the positive (+ red) lead.
The pump must be grounded to a "known ground" (battery). The ground wire must be the same size (gauge/mm2) as the positive wire.
Wire size (gauge/mm2) is based on the distance from the power source to the pump. The minimum recommended size wire is #14 gauge [2.5mm2]. Lengths of 20-50 ft. [6-15M] use #12 gauge [4mm2].
The total current draw on the circuit must not exceed 15 amps. If the pump is used in conjunction with other components, overload current protection (fuse or circuit breaker) and wire size must he for the total amp requirement of all devices on the circuit. Plumbing

SHURflo recommends at least 1 ft. [.3M] of 1/2"[13 mm] ID. flexible high pressure tubing to both ports. Ideally the pump's ports/strainer should not be connected to plastic or rigid pipe. The pump's normal oscillation may transmit through rigid plumbing causing noise, and possibly loosen or crack components.

Installation of a 50 mesh strainer is recommended to prevent foreign debris from entering the pump.

ShurFlo swivel barb fittings provide easy removal if maintenance or access is required. The fittings are designed with a "taper-seal", creating a water tight connection when hand-tightened. Always secure barb tubing connections with properly sized stainless steel clamps to prevent leaks. Never use Teflon tape or sealing compounds on threads. Sealer may enter the pump causing a failure. Failure due to foreign debris is not covered under warranty.

Rapid cycling may be caused by excessive back pressure created by one or more of the following within a plumbing system:

- Water filters and purifies not on separate feed lines.
Flow restrictors in faucets and shower heads.
- Small ID. lines. Pipe/tubing should be at least 1/2"[13 mm] I.D. for main lines.
- Restrictive fittings and connections (elbows, "T's", feeder lines to faucets, etc.)


Restrictions in a plumbing system may cause the pump to rapid cycle (ON/OFF within 2 sec.) during low flow demands. Cycling should be minimized to prevent pulsating flow, and to achieve maximum pump life.
To determine if adjustment is necessary, turn a faucet ON to lower than average flow of water. The pump should cycle, but its "OFF time" must be 2 sec. or longer. If the cycling is correct, leave well enough alone. If the pump is cycling rapidly increase the setting by turning the screw clockwise (1% turn MAX.) until the pump operates for 1 sec. with at least 2 sec. "OFF time". If cycling cannot be minimized consider removing plumbing restrictions or simply install a SHURflo Accumulator.

Potable water systems require periodic maintenance to deliver a constant flow of fresh water. Depending on use and the environment the system is subject to, sanitizing is recommended prior to filling and before using the water system after a period of storage. Systems with new components, or ones that have been subjected to contamination, should also be disinfected at; follows:

1. Use one of the following methods to determine the amount of common household bleach needed to sanitize the tank.
A) Multiply "gallons of rank capacity" by 0.13; the result is the ounces of bleach needed to sanitize the rank.
B) Multiply "Liters of tank capacity" by 1.0; the result is the milliliters of bleach needed to sanitize the tank.

2. Mix into solution the proper amount of bleach within a container of water.
3. Pour the solution (water/bleach) into the tank and fill the tank with potable water.
4. Open all faucets (HOT&COLD) allowing the water to run until the distinct odor of chlorine is detected.
5. The standard solution must have four (4) hours of contact time to disinfect completely. Doubling the solution concentration allows for contact time of one (1) hour.
6. When the contact time is completed, drain the tank. Refill with potable water and purge the plumbing of all sanitizing solution.

NOTE: The sanitizing procedure outlined above is in conformance
              with the approved procedures U.S. Public Health Service.

If water is allowed to freeze in the system, serious damage to the plumbing and the pump may occur. Failures of this type will void the warranty. The best guarantee against damage is to completely drain the water system. However, non-toxic antifreeze for potable water, available at local marine centers, may be used.

CAUTION: Do not use Automotive Antifreeze to winterize potable
                     water systems. Such solutions are highly toxic.
                     Ingestion may cause serious injury or death.

To properly drain the system perform the following:

1. Drain the water tank. If the tank doesn't have a drain valve,  open all faucets allowing the pump to operate (l5 min. ON  / 15 min. OFF) until the tank is empty.
2. Open all the faucets (including the lowest valve or drain in the plumbing) and allow the pump to purge the water from the plumbing, then turn the pump OFF.
3. Using a pan to catch the remaining water, remove the plumbing at the pump's inlet/outlet porn. Turn the pump ON, allowing it to operate until the water is expelled. Turn OFF power to the pump once the plumbing is emptied. Do not reconnect pump plumbing. Make a note at tank filler as a reminder: "Plumbing is Disconnected".
4. All faucets must be left open to guard against any damage.


For a downloadable system diagram click here. (4k) file

Pump cycles too much? Add an Accumulator tank.


Directory  |  Diesel Engine  |  Tools  |  Mailbag  |
Home Page   |  Odds n Ends    |  Boat Builders  |  Engine Page  |  Electric Page  |  News Page  |  Safety page  |  Trailering  |  More About Us   |   Related Sites   |   Special offers   |   Event Calendar   |   Opportunities