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Feed Watermaker from Dockside Water?

Discussion in 'Watermakers' started by LAM, Sep 16, 2025.

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  1. LAM, Sep 16, 2025
    #1
    LAM

    LAM New Member

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    Anyone fed a watermaker from the dockside water? Was looking at spotless systems, but started thinking maybe could just use watermaker and use water from boat tank (200 gallons) to wash. Our dockwater is actually well water and we dont often use our FCI Aquamiser 600gpd watermaker as we are in brackish water on the Chesapeake.

    Tried connecting dockside hose to Groco flush cap on strainer but seems like dockside water pressure is too high even when turn down and watermaker not priming properly. Tried asking FCI but just wanted to sell add on DTS system. Thx
  2. Capt Ralph, Sep 17, 2025
    #2
    Capt Ralph

    Capt Ralph Senior Member

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    Pickle your RO system.
    Purchase one of those SpotFree tanks and wash your boat directly from the dock water supply.
    Your RO system will last much longer.
  3. d_meister, Sep 18, 2025
    #3
    d_meister

    d_meister Senior Member

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    Chlorinated civic supply water can damage R.O. membranes.
  4. Sea Gull, Sep 18, 2025
    #4
    Sea Gull

    Sea Gull Member

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    I’m following this as I have similar thoughts and have done a bit of research.

    First off, chlorine is probably not an issue for you on well water, but for those of us on municipal water systems the answer is to prefilter with an activated carbon filter. You may even already have one built into your back flush system. By the way, the Spot Zero dock water system has a carbon filter built into it.

    On the issue of incoming water pressure, you probably just need to turn off your boost pump because there is already enough pressure in the well water supply.

    Other than ongoing maintenance, I have not found any reason not to do what you are attempting.
  5. LAM, Sep 20, 2025
    #5
    LAM

    LAM New Member

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    Sea Gull, yes we are on Well water so chlorine not an issue, but still I pre filter it twice before even comes in the boat, sediment filter and then carbon filter.

    Issue I was having was the low pressure pump didnt seem to like the higher pressure of the dockside water and system kept throwing an error. When restricted it seemed to work but needed a more consistent method. I actually bought a pressure regulator im going to connect in line and see if helps. Will report back.

    upload_2025-9-20_10-41-59.jpeg
  6. Capt J, Sep 20, 2025
    #6
    Capt J

    Capt J Senior Member

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    If running a watermaker on fresh water, you are going to need to dial down your pressure and modulate the water maker based on water flow. Instead of running 800 +/- PSI for saltwater, usually run 100 +/_ PSI for fresh water. Too much volume will blow your membranes out. You can also run a watermaker in clean brackish water such as the chesapeake if you also dial the pressures right. I would prefer to run it from sea water at your dock than this contraption you're trying to use if the sea water at your dock isn't stagnant. You are going to go through a TON of well water to fill your water tank as most will be bypassed by the watermaker.
  7. Capt Ralph, Sep 20, 2025
    #7
    Capt Ralph

    Capt Ralph Senior Member

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    Rite
    Water-makers only make about 5% fresh water of total flow.
    After your dock filters, a Spot-free bottle would still be the answer.