Sea Water Wash Down & Toilet Flush

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Location: Hastings on Hudson, NY

Sea Water Wash Down & Toilet Flush

Post by BillBerner » Tue Aug 28, 2018 2:31 pm

I worked up a system that gives me a pressurized wash down in the anchor locker, as well as the ability to flush the Electric toilet with sea water when desired. It only needs a single pump.
I was able to rig it so there’s no chance of tainting my potable water system with seawater.
If anybody’s interested in how I did it, I’m happy to describe it and provide pictures
Bill Berner
#66, Stamford CT.

S/V Tavish B.
Posts: 9
Joined: Wed Feb 03, 2016 12:41 am

Re: Sea Water Wash Down & Toilet Flush

Post by S/V Tavish B. » Sat Nov 17, 2018 10:08 am

I would be interested in seeing your set up, I've been considering adding a raw water option for the head, to extend my fresh water usage.

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Posts: 108
Joined: Wed Oct 13, 2010 11:50 am
Location: Hastings on Hudson, NY

Re: Sea Water Wash Down & Toilet Flush

Post by BillBerner » Sun Oct 13, 2019 9:50 am

Unfortunately I couldn't attach a pdf of instructions, so here's the text in the body of the post. Pictures and electrical drawing attached as jpegs.


Installing a Combo Seawater Wash Down/Electric Head Flush System
1 Johnson Aquajet Washdown kit. The kit came with a pump, strainer, fused switch, fittings, coiled hose, & nozzle.
1 3/4” Bosworth Diverter Valve 1 3/4” vented loop
1 3/4” tee
2 3/4” thread to barb adapters
4 90 deg elbows
26 hose clamps (approx.)
25’ 12/2 marine grade wire
25’ 3/4” water hose
1 12v 20 amp double pole single throw switch
Yellow Butt splices
Yellow Ring terminals
Starbord or other backing material for pump mounting
Added Later: 1- 3/4” Bronze Inline Ball Valve
Soup to nuts I spent around $300.

1. Pump & Toilet Plumbing installation
This was the hard part, for no other reason than limited space.
At the risk of stating the obvious, all hose connections below the water line should be double clamped.
In the owners cabin -
1. To mount the pump, 5200 a piece of your favorite backing material - I used
starboard - to the inside of the hull in the small locker that the toilet intake thru hull is located (floor level, portside, , just aft of the bed in the fwd cabin). Pre- drill pilot holes for the pump mounting screws b4 you install the backing material. Don’t mount the pump yet!
2. Remove the existing hose from the raw water thru hull.
3. Using a really small piece of hose, connect one of the tees to the seacock.
4. Cut a 1’ piece from the hose you removed.
5. Cut 2 - 6” or so lengths from the hose you bought
6. Cut a short piece of hose, just long enough to join 2 tees to make a U.
7. Rotate the strainer inlet port so it faces the rear of the pump. Attach the 2 - 6”
hoses to the U. Connect one end of the rig to the inlet port of the strainer.
8. Use another very short length of hose to connect the last elbow fitting to the
output port of the pump.
9. Connect the inlet hose rig to the seacock, and the output to the raw water hose
that is routed into the Holding Tank Locker behind the toilet.
10. Mount the pump to the backing material.
11. Clean up the blood from that has dripped onto the cabin sole from your scraped knuckles. Get up, stretch, take a break. You’ll need it.

In the head -
1. In the locker where the holding tank is located, run the existing raw water hose up to just above the vented loop for the toilet fresh water feed.
2. Install a tee fitting vertically with the short barb facing the hull.
3. Connect the upward facing long barb to your new vented loop.
4. Mount the diverter valve just forward of the discharge valve handle under the
holding tank
5. Using a length of 3/4” hose, connect the output side of the vented loop to one of
side of the Inline ball valve, using a thread to barb adapter.
6. Using another length of 3/4” hose, connect the other side of the Ball Valve to
one of the inlet ports of the diverter valve.
7. Cut the hose leading from the electric toilet vented loop to the toilet inlet at the
appropriate spot, and connect the supply side to the other inlet port of the
7. Connect the hose leading to the toilet to the output port of the diverter.

2. Plumbing the Wash Down System
In the Anchor Locker
Cut 1.5” dia. hole below the anchor rode cleat to accommodate the hose fitting supplied with the wash down system. The hole needs to be that big to allow the hose clamp to pass thru, and may need some additional Dremel, or similar tool, work to make it large enough. I chose this location to guarantee there would be no kinks in the hose.

In the cabin
Remove the cover of the cable chase above the port side shelf next to the bed. Route 3/4” aft through the clothes locker into the holding tank locker with enough length to connect it to the short barb of the tee you installed on the supply side of the vented loop. Leave sufficient length to avoid linking the hose. Run the hose forward thru the cable chase, and finally out the hole you cut in the anchor locker bulkhead. Use a piece of bailing wire wrapped around the end of the hose as a messenger to get from the cable chase thru the hole.
Secure the hose to the deck/hull thru bolts with zip ties.

Back in the Anchor Locker
5. Secure the washdown hose fitting to the hose, clamp it, and screw the fitting to
the anchor locker bulkhead.

Back to the Head
1. Connect the other end of the hose to the the short barb of the the tee.
That, finally completes all the plumbing. Using the diverter you can now route either fresh or sea water to the toilet.

3. Electrical Installation
Critical here is that the system is wired so that the existing toilet switch controls the flow of raw water to the toilet. If the the seawater pump were able to run continuously while raw water was routed to the toilet, the result would be very unfortunate, to say the least.
1. Cut a hole under sink, next to the toilet switches to mount the double pole single throw switch you bought.
2. Cut another hole next to the first for the switch that came with the pump kit.
3. Unmount the toilet switch from the cabinet.
4. Connect the hot and ground of the pump in the owners cabin to a length of 12/2 marine wire. Run the wire from the pump through the locker behind the toilet and down into the cabinet under the sink, with enough length to connect the hot leg to the pump switch.
5. Run a length of 12/2 from an unused breaker on the 12v panel to the same location under the sink.
6. Connect the ground wires of the two runs together.
7. Connect 3-way butt connectors to both leads on the pump switch.
8. Connect the + wire from the breaker to one of the crimps of the 3way butt
connector on the line side of the pump switch.
9. Connect the + wire from the pump to one of the crimps on the load side of the
pump switch.
10. On the toilet switch, cut the + wire on the line side of the switch. Reconnect the
wires using a 3-way but connector.
11. On the load side of the toilet switch cut the wire leading to the toilet solenoid.
Be sure it’s the solenoid wire, NOT the macerator pump wire.
12. Using a short jumper, connect the open crimp of the line side wire of the raw
water pump switch to the line side wire of the toilet switch.
13. Using another short jumper, connect the open crimp of the load side wire of the
raw water pump switch to the load side wire of the toilet solenoid.
14. Mount all the switches to the cabinet.

CONGRATZ! Your done.

4. Using the System
Fresh Water Flush and wash down hose.
Set the diverter valve set for fresh water Close the Inline Ball Valve
Set the double pole switch to “off” Turn the pump switch “on”
The toilet and wash down system will work normally. The nozzle on the washdown hose will activate the wash down pump, just like opening the faucet activates your fresh water pump.
For added safety, I leave the raw water pump switch off and close the sea cock unless I’m about use the washdown hose.

Raw water Flush
Make sure the pump switch is off.
Turn the double pole switch on.
Set the diverter for raw water
Open the Inline Ball Valve
The toilet switches will now activate the raw water

For an extra measure of safety, I always close the seacock and turn off the breaker for the system when it’s not in use.
Raw Water Flush Washdown Electrical.jpg
Raw Water Flush Washdown Electrical.jpg (169.81 KiB) Viewed 73 times
Pump.jpeg (158.03 KiB) Viewed 73 times
Loop.jpeg (147.29 KiB) Viewed 73 times
Locker.jpeg (191.79 KiB) Viewed 73 times
Bill Berner
#66, Stamford CT.

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