Disappearing water problem ...

jff

jff

Member
Mar 29, 2008
510
Atlanta
Boat Info
2017 Crest Pontoon
Engines
Yamaha
So here's the scenario. I fill up my water tank all the way on a Wednesday. I come back to the boat Friday and it's still full. I turn on the heads and water pump and take the boat out for about a 1-hour run (on and off plane twice). During the run we use no water. When I return to the dock and tie up I check the water and it's showing 1/2, somehow on that run I used roughly 1/2 a tank of water. I don't remember the fresh water tank size on my 48 DA but it's not tiny, that's a lot of water! So of course my question is, where is the water going and how/why. My only theory at the moment is that perhaps there is a leak that only manifests itself either a) when the pump is on or b) when we go on/off plane and the water is going into the bilge and getting pumped out. I don't think it is the water pump because we had the same thing happen last weekend except we spent about 6 hours tied up with the water pump on and there didn't seem to be any loss of water. Anyone have other ideas of what it could be or how to troubleshoot this further?

Regards,
Jason
 
Leaking Water heater?
Is there water in your bilge?
Is your pump on?
Check the transom shower
 
Good point - I forgot to mention that I also turn on the water heater when I get to the boat. The only reason I'm iffy on it being a leak like that is I'm pretty sure last weekend there was not significant water loss when we were tied up for six hours (with water heater and pump on). That's what made me think it was somehow related to running the boat and/or going on/off plane. But I could be wrong. There's always a little water in my bilge but this would be a lot of water (1/2 a tank), I would think those bilge pumps would have to be pumping quite a bit to get rid of that much water.

Regards,
Jason
 
My water heater just sprung a leak and when I turn on the water it would pressurize the tank and then slowly push water out of the heater which would make its way into the bildge.

Apparentley we are supposed to flush the heaters frequently to minimize and reduce galvanic corrosion.

Now I am looking to get a new heater and or bypass as I really do not use it.
 
Turn on the water pump and listen , it should pressurize and hold until you open a faucet,, if it pumps on and off you have a leak somewhere....
 
There must be but the strange thing is that last weekend we started on full, used half a tank up on the 20 minute ride to our cove (without using any water I can remember) then sat in the cove for six hours and didn't seem to use any up. If there was a leak it would seem like it would have continued during that time (the water pump and heater were on the entire time). That's what made me wonder if somehow it was related to running the boat/being on plane ...

Regards,
Jason
 
How do you know it's full? Are you trusting a gauge or are you able to see the tank?
 
I'm trusting the guage ... but I know it's full each time I fill it because I fill it until the water overflows (and then the guage inside says full), and when the guage says 1/2 I have to add a lot of water to get it to overflow outside again - so the guage sure seems accurate anyway.

Regards,
Jason
 
Perhaps the heat exchanger is perforated and pulling water down to the level it passes through the heater.

Check to see if your water heater has two black hoses going into and out of the heater to the engine. Some heaters use hot water from the engine running through the heat exchanger to heat the water.
 
Going to do some experiments, visual tests, exploration, etc. Thanks for the feedback/ideas everyone.

Regards,
Jason
 
Fill the tank, turn on the pump, and remain nearby where you can hear it run. Once the lines are pressurized, you shouldn't hear the pump kick on again (unless you open a faucet, of course). If you hear the pump running intermittently, you have a leak on the pressure side of the system.

If that's not the case, it's a leak in the tank itself. I'd inspect the area surrounding the tank.
 
if you hear the water pump running when all the faucets are of, the leak is in the lines. Check connections under the sinks, water heater connections, etc. if the leak is from the tank, that is before the freshwater pump and the pump will not kick on.

that much of a loss sounds like it is on he pressure side.

Dont foget to check the freshwater water washdown, or aft deck shower if you have one.
 
Do you have water in the bilge? If not, how about a washdown in the anchor locker? You should hear the water pump running if the washdown is leaking, but the anchor locker would drain to the outside of the boat.

Good luck...
 
My fresh water leak was the pvc elbow on top of the tank. The water went into my center bilge and was pumped out by the bilge pump.

What does the quantity do if you start out at 1/2 and go out on plane? If it stays at 1/2, I would suspect the tank. But first ensure your pump isn't running full time as suggested earlier.
 
Carter and Sue,

I like your extended cockpit bimini. I assume it was custom. Can you share the costs and did you have it done local?
 
You mention a correlation between running the boat and water loss.... I had a small drip at one of my fresh water T-joints in the bilge and the vibration of running boat would cause greater water loss (the pump must be on). I would look for a small drip/wet spot while tied to the dock (pump on), then wiggle the connection and see if the drip turns into a stream...? It did on my boat and for a few bucks + 5 minutes of your time.... Problem solved ! (replace the connector)
 
I know exactly what it is. I had the same problem and had hardly any water in the bilge and just felt I had a leakey fresh water pipe and the water was being pumped out of the bilge. After weeks of looking at all my fresh water connections and pipes I was outside the boat swimming and I noticed water spewing out of a vent hole. Checked the documentation and it was coming out the hotwater heater overflow. After replacing the temperature/pressure relief valve on the hotwater heater, I no longer lost fresh water. Evidently the valve was stuck open.
 
Interesting - I spoke to a local MM Captain yesterday who suggested it could be just that. I'm going to have it checked, thanks for the advice/ideas everyone!
 
I have the same problem, water leaking out through the vent from the hot water tank.where did you get the replacement pressure relief valve?
Regards,
Manfred
2004 420 Sedan Bridge
 
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