Water Tank Won't Feed

[rnp]

Just returned from a cruise with a few gallons of fresh water left. I refilled all of the 5 tanks at the slip and now one of the tanks, which I can see is full, will not feed to the fresh water pump at all. There is zero water flow. The pump works fine. All of the other tanks feed fine. All 5 tanks worked fine during the cruise. I thought of a blockage, but can't think of how a total blockage could occur so suddenly. The boat is plumbed with semi-rigid pex-like piping, so I can't just remove a few hose clamps to test for flow. I removed the tank monitor sender, and there was no vacuum in the tank.

Any and all ideas welcomed.

 

[JamesG161]

All fresh water tanks must have a "air vent" to let the air in, as water flows out. If that vent is blocked (Insects can make homes in them), then you will not get water flow out.

On my boat the tank vents are actually "floor to deck" grab poles and are vented in a way to prevent "deck wash" flowing into my fresh water tank.

If you can see your "no flow" tank, the vent will be off the top of the tank. Trace the vent line to the air. If the vent is in your cabin, someone may have accidentally blocked the vent hole.

Jim...

PS: all tanks have a vent for in/out flow.

 

[rnp]

You're right about vents Jim. That's why I removed the tank monitor sender so the tank would have a big hole to serve as a vent. Even with that hole open, there was no flow at all.

All fresh water tanks must have a "air vent" to let the air in, as water flows out. If that vent is blocked (Insects can make homes in them), then you will not get water flow out.

On my boat the tank vents are actually "floor to deck" grab poles and are vented in a way to prevent "deck wash" flowing into my fresh water tank.

If you can see your "no flow" tank, the vent will be off the top of the tank. Trace the vent line to the air. If the vent is in your cabin, someone may have accidentally blocked the vent hole.

Jim...

PS: all tanks have a vent for in/out flow.

 

[JamesG161]

I removed the tank monitor sender

Duhh I missed that.

I am assuming you leave all tanks water exit valves open to a manifold that feeds the fresh water pump. If true, the water levels of all tanks will be "equal". If not, you might try backflowing one tank to the culprit tank. That may eliminate that line as free to flow or unblock a "piece of trash" that settled to bottom when tank went empty.

Another test...
Isolate good tanks, and use your dock fill hose to back flow thru a sink spigot, to the culprit tank. you can buy a garden hose to sink spigot adapter. Note: don't let the marina water pressure get to high, just crack the valve.

That will verify an open line to your culprit tank.

Jim...

 

[rnp]

I isolate the tank valves to the manifold and leave a max of 2 open at a time. I've found that there's less chance of flow problems that way on my boat. The back flow idea with marina water sounds good. I'll try it. Thanks.

rnp

 

[LittleCreek]

There is a blockage some wheres. Do a back flush and see if it clears.

Pex is great to work with. You can snip it and install a union or test fitting in less than a couple minutes. If you don't have a ring compression tool, the local plumbing supply will rent you one for 5-10 bucks.

 

[rnp]

PROBLEM FIXED

Thanks for the suggestion about back flushing the water. It worked.

For the archives in case anybody else has this problem, I couldn't backflush through a spigot. I had to backflush between the water pump and the tank. On my boat at least, the pump seemed to prevent any backflow.

Now I just need to figure out how to remove whatever was blocking the flow from the tank.

 

[Bill Roosa]

If that tank water level is below the level of the pump inlet you probably just have an air leak in the tank to pump line or the valve stem. since you have the pump primed and a vent and it worked before the only other option would be something introduced into the tank during filling that is blocking the tank outlet. that seems unlikely as you would have gotten something out of the tank before it blocked the tank outlet.

 

[JamesG161]

I couldn't backflush through a spigot

Double Duhhh on my part.

Most boats, even mine, have on demand "piston like" pumps that have back flow preventer "check valves". I was thinking Bilge type pumps.

But...

I am glad you got er done.

Note Guess: a piece of rubber, certain calking, level sender gasket or other floating, fairly large, trash item is in your tank. One good thing is it was large enough to restrict the tank discharge and NOT go in to your water pump and jamb it.

Depending own how large your sender hole is and if your bilge can handle the overflow, I would slowly "back flow/over flow" that tank until the trash "floated" out through the sender hole and NOT into your bilge pump.

If it was NOT a floater, then you should have seen the stoppage before low level tank.

Jim...

 

[centerline]

Double Duhhh on my part.




If it was NOT a floater, then you should have seen the stoppage before low level tank.

Jim...

your batting a triple...
as the op said, the water would not flow out of the last tank at all so it was full. this means the blockage IS a sinker and NOT a floater that is causing the problem...

 

[JamesG161]

Be willing to bet a cookie, I just stole HOME. .

Just returned from a cruise with a few gallons of fresh water left. I refilled all of the 5 tanks at the slip and now one of the tanks, which I can see is full, will not feed to the fresh water pump at all.

He asked for suggestions, he didn't qualify "stupid or not"

Good luck in finding the debris. I hope it isn't inside your water pump.

Remember free advise is worth what you pay for it.....
Jim...

 

[All U Get]

So its not a valve problem? I can't see far away anymore so a picture would help.
Do you have a valve at each tank?
All U Get

 

[gettinthere]

Run the water out of that tank until it clogs again, then you will know where the debris is.

Then use the tank sender port to feed a shop vac hose down to the outlet port to suck up the junk. You may need to tape a smaller hose to the big shop vac hose to make the reach

 

[Ron20324]

During a 16-day cruise, my Benny water tank wouldn't put out either. I almost bought a new pump, but there were none available. I found a check valve in the tank exit pipe that had stuck closed. Took it out totally, and all has been okay for years.

 

[nlneilson]

Run the water out of that tank until it clogs again, then you will know where the debris is.

Then use the tank sender port to feed a shop vac hose down to the outlet port to suck up the junk. You may need to tape a smaller hose to the big shop vac hose to make the reach

Very good suggestions. A way to apply pressure as well as vacuum to the outlet line may help dislodge the obstruction. Removing the outlet line from the tank can determine if the blockage is actually in the tank or the line/s.

 

[NotCook]

Glad you found a solution.

We have a similar issue with our center water tank and I have disconnected the feed line from the tank from the manifold and both sucked and blown on it without relief. Fortunately, the connection to the tank is Burke in the keel at the base of the tank and unreachable. In almost at the point of running another exterior intake from the top and dropping it into the tank. These are the kind of things that make me crazy!