Potable Water/Raw Water Interconnect Modification

[Midnightsun]

Happens every now and then we run out of water in the tank after several days at anchor no matter how careful you are being there is only so much water on board. The main issue is the toilets will not flush as the draw is from the potable water tank and no water means no flush and an obligation to return to port.

The modification is to install a connection between the pressurized side of the potable water system and the pressurized side of the wash down pump. Using a solenoid valve and a filter to remove sediment and a few T connections is all it takes. This is the same connection all boats use to interconnect dock water to the potable water system except now it will be the washdown pump circuit.

Will add a 5a breaker in my panel to energize the solenoid just below my water pump breaker as this one needs to be off and visa versa when deactivating it. If I want lake water, turn off water pump breaker, turn on solenoid breaker, done deal.

This will work well for us as our boating waters are fresh water and almost drinkable. The idea is to use the feature when away from port for several days knowing we will probably run out. Will activate it when we take showers and maybe when we do dishes, the idea being to use less water from the tank.

[Midnightsun]

This is the solenoid I am using. https://www.ebay.com/itm/1-2-NPT-12V-DC ... 2749.l2649

This is the breaker I am using. https://www.ebay.com/itm/NEW-Blue-Sea-7 ... 2749.l2649

This is the water filter I am using which is available on Amazon USA for $26 or Amazon Canada for $60 . the nice thing about this unit is it takes standard 10" x 2 1/2" filters which are dirt cheap. The unit for the application is perfect as the filter is 50 micron which is fine but not so much so as to block to quickly. I see no reason why I would need to change it out during the season but do plan on doing so each spring. There is already a strainer on the wash down pump intake so this will take out the bigger stuff before it sees this filter. The unit comes with no less than 3 cartridges which should keep you going for 3 years. The filter also incorporated a built in bypass valve in the head which is convenient for bypassing, or turning it off manually as can be seen in the picture.

[Midnightsun]

All done, found out that the solenoid valve only holds water back in one direction so I had to add an in-line check valve to prevent flow from potable water system to washdown when the potable water pump is on. https://www.homedepot.com/p/Homewerks-W ... /204237824 Found a nice spot to mount the filter/solenoid.

The white thing beside the water tank tucked in there is the check valve. Mounted it close to where I interconnected to the potable water system line only about 6 inches away. This way when not in use there is no pressure from the potable system farther down the line which would pressurize the filter, solenoid and other connectors downline. Not that this is a problem as they are designed for this however it is always a good idea to not have them pressurized.



Picture of mounted filter/solenoid. Mounted to a piece of 2x8 glued to the bed frame fiberglass. Stainless custom made mounting bracket secured to 2x8 with 4 screws which makes for easy filter changes and use of built into the top filter/off/bypass valve. Winterization should also be a breeze.



Need to do a final leak test as I obviously need to be in the water to activate the wash down pump other wise the installation is complete.

Will post a picture eventually of activation breaker in the DC panel.

[Midnightsun]

Here is the picture of the DC panel where I located the breaker that serves as a switch to activate the interconnect solenoid. It is the white one labeled "river water". Thought it best to use a 5A breaker just below the washdown pump and water pressure pump. flip off water pressure, flip on washdown and "river water", now the interconnect is operational. Endless supply of water for showers and flushing.



AGAIN I WILL MENTION I AM ABLE TO DO THIS BECAUSE OF THE CLEANLINESS OF THE FRESH WATER WE BOAT IN. I DEFINITELY DO NOT RECOMMEND THIS IF THE WATER YOU ARE IN IS POLLUTED OR IN SALT WATER.

[Midnightsun]

Leak test done, no issues, works like a charm.

[RGrew176]

I just love a happy ending.

[Midnightsun]

Got to actually try it out last weekend, works absolutely perfectly. Was concerned the shower pressure would be low but not the case at all. Endless water.

[pepmyster]

Very, very well done project!!

[Midnightsun]

Just came back from 4 days on the hook. First time I managed to come back with 3/4 of a tank of water and we used water like there was an unlimited supply! Oh wait, there was. I thought this was a good idea but it turned out to be a fantastic one. Love this modification and if you boat in clean water I highly recommend it.

[daveS]

On my "to do" list for the spring.