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Old 06-19-2020, 06:10 PM   #1
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How much should remain in fresh water tank?

My EVO should have a 56 gallon tank. After the pump quits pumping any water, and I pull the drain, it appears to drain 10+ gallons. Shouldn't the pump be able to pick up water from near the bottom of the tank?
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Old 06-19-2020, 06:59 PM   #2
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Did you account for the amount of water in the water heater? It's either 6 or 10 gallons of your 56.
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Old 06-19-2020, 07:12 PM   #3
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Yes, I make sure that the entire system is full, when filling. Still what seems like a LOT of water when draining, after the pump can't get any more out.
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Old 06-19-2020, 07:18 PM   #4
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Mine says it has a 42gal tank. I have never been able to get more than 30gal into it. My water heater is 6 gallons and the lines hold 1.5gal based on my antifreeze usage...still short 4 gallons either way. No truth in advertising no matter how its calculated.

It sounds to me that the OPs problem is the intake line is a bit too short in terms of capacity or the RV was at a bad angle...
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Old 06-19-2020, 07:52 PM   #5
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Mine says it has a 42gal tank. I have never been able to get more than 30gal into it. My water heater is 6 gallons and the lines hold 1.5gal based on my antifreeze usage...still short 4 gallons either way. No truth in advertising no matter how its calculated.

It sounds to me that the OPs problem is the intake line is a bit too short in terms of capacity or the RV was at a bad angle...

You know, I've never measured how much I can get into it, but it is parked on the level on my RV pad when filling. The short intake line is my concern, hence the question. When the pump can't get anymore out, how much water should remain? Mine seems excessive, to me.
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Old 06-19-2020, 08:10 PM   #6
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My EVO should have a 56 gallon tank. After the pump quits pumping any water, and I pull the drain, it appears to drain 10+ gallons. Shouldn't the pump be able to pick up water from near the bottom of the tank?
If you got the 56 gallons from the brochure or website, you do know there's fine print at the bottom. It says they can make changes to everything listed, at any time. There have been cases of them going to smaller tanks midseason.
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Old 06-19-2020, 08:27 PM   #7
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If you got the 56 gallons from the brochure or website, you do know there's fine print at the bottom. It says they can make changes to everything listed, at any time. There have been cases of them going to smaller tanks midseason.

LOL, yer killin' me, Dan! The question is about how much water should remain in a tank where the pump can't get at it.
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Old 06-19-2020, 10:15 PM   #8
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Well, I would think quite a bit could remain in the tank. Now, I havent measured exactly but my tank is about 6 feet wide and 3 feet long at the bottom. If there is only an inch of water then that is around 10 gallons. I know the pick up tube is not at the very bottom of the tank. So I could have 15 gallons left when the pump starts sucking air. That is a guesstimate anyway.
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Old 06-19-2020, 10:25 PM   #9
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You know, I've never measured how much I can get into it, but it is parked on the level on my RV pad when filling. The short intake line is my concern, hence the question. When the pump can't get anymore out, how much water should remain? Mine seems excessive, to me.
Yea 10gal is too much. I am not sure how the hoses connect inside the tank. You may be able to trace from the pump back to see if it got pulled a bit but I expect that there would not be a way to move it or it would eventually come all the way out.

If you have a gravity fill you could try checking by putting a boroscope in the fill to see where the pipes are. Maybe it is coiled inside and you could just pull some out but I doubt it would be that easy.
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Old 06-20-2020, 12:50 PM   #10
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I have a 2017 EVO 2360 and have seen the same thing. When my water pump starts drawing air I can pull the drain and get almost 10 gallons out of the tank. I'm going to look into rerouting the intake so it is lower in the tank.
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Old 06-20-2020, 12:57 PM   #11
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My EVO should have a 56 gallon tank. After the pump quits pumping any water, and I pull the drain, it appears to drain 10+ gallons. Shouldn't the pump be able to pick up water from near the bottom of the tank?
Fact is the outlet is mounted on the side of the tank which leavbes water i the bottom of the tank . many tanks also have a drain that is at the bottom of the tank . So you could tap into the bottom drain for pump pick up and plug the existing out put for the pump and get more water out of the tank
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Old 06-20-2020, 01:28 PM   #12
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LOL, yer killin' me, Dan! The question is about how much water should remain in a tank where the pump can't get at it.
Sorry, misunderstood your post.
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Old 06-20-2020, 01:36 PM   #13
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Originally Posted by MR.M View Post
Fact is the outlet is mounted on the side of the tank which leavbes water i the bottom of the tank . many tanks also have a drain that is at the bottom of the tank . So you could tap into the bottom drain for pump pick up and plug the existing out put for the pump and get more water out of the tank
Correct.
Many pump supply ports are on the side of the tank and tend to suck air even when there is 10-15 gallons of water left in the tank.

This condition is also why it is often recommended to not put antifreeze in the fresh tank when winterizing because it would take lots of gallons just to get the level high enough for the pump to pick it up.

There have been several posts (especially from boondockers trying to get every gallon) on teeing off the drain line for the pump supply.
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Old 06-20-2020, 02:17 PM   #14
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Thanks, all. It looks like this may be normal. My trailer is parked at the curb out front, which makes it advantageous for the pump, as it isn't level. I ran the pump until it wouldn't even spit a bit, then drained the tank into a measured bucket. 5.5 gallons came out, meaning 7-8 gallons when level.
One thing I learned is that the toilet and faucets will run for a long time after the pump starts spitting air; probably another gallon, or two.
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Old 06-20-2020, 02:54 PM   #15
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I suppose the "easy" way to get all the water would be to hook a hose on the FW tank drain and connect it to the winterization port...then you are drawing from the lowest point. It would work in a pinch where you could not get more water. I would use my antifreeze hose for that but would not leave it hooked up that way.

Mine does pretty good. When I put 10gal in I am able to flush for a while on the road. Never measured after the pump stopped sucking water so I will have to check that.

If anyone fixes theirs I am curious how difficult it turns out to be.
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Old 06-20-2020, 03:32 PM   #16
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Look at the tank and where the outlet to the pump sits. If it's like nearly every tank I've seen it's on the side of the tank some distance from the bottom so a fitting can be screwed into it and can't possibly get all the water out unless you tip the tank toward that outlet. The only standard for useful capacity is it's always less than capacity.

Not only the outlet but filling tank to full capacity may not be possible so that 50 gallons is something less.

The fitting below appears to be a full inch or more off the bottom of the tank.

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Old 06-20-2020, 08:39 PM   #17
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I have a driveway that slopes down - not excessive, but does have a slope. My problem is I think I'm filling it up, but the tank fill hose is in the direction of the slope and starts running out the gravity connection when probably ⅓ full. So I've learned, where ever I am, that tank is going to appear full and really isn't andI will be short of water due to a poor tank fill design.
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Old 06-20-2020, 09:15 PM   #18
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I have a driveway that slopes down - not excessive, but does have a slope. My problem is I think I'm filling it up, but the tank fill hose is in the direction of the slope and starts running out the gravity connection when probably ⅓ full. So I've learned, where ever I am, that tank is going to appear full and really isn't andI will be short of water due to a poor tank fill design.
I purchased one of these https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 and found it surprisingly helpful and accurate.
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Old 06-20-2020, 09:23 PM   #19
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I purchased one of these https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1 and found it surprisingly helpful and accurate.
I like the water meter gauge idea, but it won't help get water into a tank that is spilling that water back out because of a slope. Poor design on my RV. Had two previous TT and never had this problem.
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Old 06-21-2020, 12:54 PM   #20
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We have never used ours. Flagstaff 829 fks is 10 years old.
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