Trick to knowing when water tank is full

[CallMeBigPopUp]

Hi all, first time posting here however I have been lurking through posts for a month or so now and have found a bunch of great info. We are new to rv camping, have been tent campers all our lives, but decided to upgrade this year and bought a 2021 rockwood 2318g.

I just got done de-winterizing everything and found it was a pain to know when the water tank is full without overfilling it or looking underneath the camper to see the water tank.

This is a potentially stupid question, but was wondering if anyone had any trick to knowing when the tank was full without overfilling. Or maybe overfilling a little isn't a big deal and I am over thinking this? I noticed it had a warning about overfilling the tank could cause damage, so that is where my concern for that came from.

Thanks in advance and happy camping!

[Iwritecode]

Originally Posted by CallMeBigPopUp

Hi all, first time posting here however I have been lurking through posts for a month or so now and have found a bunch of great info. We are new to rv camping, have been tent campers all our lives, but decided to upgrade this year and bought a 2021 rockwood 2318g.

I just got done de-winterizing everything and found it was a pain to know when the water tank is full without overfilling it or looking underneath the camper to see the water tank.

This is a potentially stupid question, but was wondering if anyone had any trick to knowing when the tank was full without overfilling. Or maybe overfilling a little isn't a big deal and I am over thinking this? I noticed it had a warning about overfilling the tank could cause damage, so that is where my concern for that came from.

Thanks in advance and happy camping!

Are you asking about the fresh water tank or the hot water tank?

[CallMeBigPopUp]

The fresh water tank.

Originally Posted by Iwritecode

Are you asking about the fresh water tank or the hot water tank?

[kenandterry]

Most onboard water tanks have an overflow line.
When it comes out of there, you’re full.
If you want less, you’ll have to check your inside indicator, but they’re not perfect.

[Electra glide]

I bought a inline water meter for my hose and just use that to tell. Mine is 100 gals and I don't always need it full so it's nice to be able to stop around 50 gallons with the meter.

[Thomas ho]

you cant over fill a water heater!!! over fill the tank parked , no big deal .traveling , puts lots of strain on tank straps , some older trailers.///// 15 / 20 gallons ok. need full to camp in the boonies ! it will be a few years usually for a tank to fall ,if it ever does fall. tank support info is on this web site if you see it occuring.

[ben31]

If you don't want to have the water come out of the overflow tube (not usually a big deal), you can buy the following and keep tracl of how much you put in:
https://smile.amazon.com/gp/product/B0006IX850

[Stormy Dayton]

At home, I know that when full on, my hose delivers about 4 gallons a minute, so I time it. On the road I time how long it takes to fill a 2.5 gallon bottle, (a spare container). It's not exact but close. . . .

[Tundra 2014]

Count how long it takes to fill. If you want 1/2 as much water in it, cut fill time in half, ETC.

[5picker]

Filling a fresh water tank until it overflows isn't a big deal... unless...

1. You fill it too fast. If you put water in the tank faster (under pressure) than you can vent it, you risk the danger of bulging the tank sides and buckling the tank supports or even buckling the floor!

2. On some units, when the tank starts to overflow, there can be a siphoning effect that will pull some of the water back out of the tank leaving you less than full.

I've never seen the need to have a race to fill the tank. Slow and steady and turn off the supply at the first signs of overflow. NOTE: overflow drainage and some spitting out the vent are two different things.

I too often use one of the garden hose meters to let me know how much I've put in.

[Leatherman]

I use one of these so I know how much I put into my fresh water tank:

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Easy way to know...

[donkro]

Easy peasy, can you see your tank? I can see mine, or I usually just let it go to overflow. My tank is inside under the bed, so is supported by the floor, also won't freeze, easy to view.

[5picker]

Originally Posted by donkro

Easy peasy, can you see your tank? I can see mine, or I usually just let it go to overflow. My tank is inside under the bed, so is supported by the floor, also won't freeze, easy to view.

Of the many R/Vs I've had over the years, only one truck camper could I see the tank. The rest were/are buried up in the frame and covered by the underbelly. Not so easy peasy.

[jimmoore13]

Since you posted in tent campers and popups (and based on your username), I'm going to assume a gravity fill.

Gravity fill tanks are somewhat difficult to "over-fill". Use one of these to adapt your hose to the fresh-tank fill port. https://smile.amazon.com/Camco-Shuto...1013424&sr=8-2 Note that this adapter is substantially smaller than the fill pipe, so water can easily back-flow around it and dump out on the ground once the tank is full.

As you fill one or both of these things will happen:
1) water will gush out the fill port around that adapter;
2) water will gush out the air vent that allows air to escape the tank as you fill.
(The air vent almost always shares space with the fresh tank fill port in a plastic nacelle on the side of the rig.)

Caution is advised, however. A freshwater hose (sanitary garden style hose) under 50 PSI of household water pressure can easily fill the fresh tank faster than water can escape. The pressurized water can pressurize your fresh tank faster than water can spill out. This is not good for the fresh tank...which is just plastic and is already straining under the load of containing 10 to 100 gallons of water.

So, a bit of blow-back out the fill pipe and/or air vent is not a problem. But you should be present and attentive to turn off the water supply quickly after that starts. The Camco or similar adapter has a handy 1/4 turn ball valve for just this purpose. A minute or two is no problem...10 to 20 minutes of water going in under pressure could damage connections or even damage the tank.

Evidence of this concern is that, once your tank is full and gushing out the fill pipe/air vent, the force of that gushing increases steadily as pressure builds in the tank. Stay nearby and shut off the water supply promptly.

By the way, your PUP may not have this feature, but as tank size grows, many manufacturers add an overflow hose to the top of the tank. The overflow hose is under the rig, and you have to watch it to see when water starts spilling out of the tank. Water never backflows out the fill pipe, and if it does, the tank is pressurized more than it should be. Once this spillage starts, water will continue to be siphoned out of the tank until air breaks the siphon. My tank will lose about a gallon or so in this process. That's how it's designed to work.

Some will urge that you add a valve to the end of that hose to shut off once the spillage starts...to save that gallon or so. Also, on uneven terrain, the tilted tank may, once again, spill out more water. But, add that valve at your peril. If you forget to open it when filling, you now have a quite large amount of water in a plastic tank, and waiting for spillage at the gravity fill and/or air vent can, in essence, overfill the tank. A big deal? Probably not, but the overflow hose is on there for a reason. Defeat it at your own risk.

One more tip. Sloppy construction technique can lead to a sag in the air vent hose that allows air to escape from your frest tank as it fills. Inevitably this sag fills up with water. Once full of water, it blocks the air from escaping the tank, and your life becomes miserable, because you need to trickle water into the fresh tank as you fill. If you discover that your fresh tank won't accept water at full pressure from the hose, that's likely th be the problem. Crawl under the camper, identify the air vent hose, see if it has a sag, and deal with it. Sometimes you can use zip ties to support the hose to something like the fill pipe/hose, or, as a worst case scenario, you might have to shorten the hose. Usually zip ties or tape will get it done.

(Note that many larger campers have a "pressure" fill in which you throw a knob from "city" water to fresh tank fill...but that's another discussion covered here:

https://www.youtube.com/watch?v=Mgu5mKl1DRE

.)

[jimmoore13]

P.S. Forest River has a video on filling the fresh tank using gravity fill. I think it's a horrible video. The demo shows stuffing a garden hose end into the tank (which won't fit) and recommends simultaneously monitoring the frest tank meter on your control panel to avoid "siphoning." But duh, PUPs don't usually have that panel, and if they do, is it visible with the camper folded? Probably not.

As others have said, if your rig has a 50 to 100 gallon fresh tank, you MIGHT want to only fill it partway for on-the-road convenience with the bathroom, etc. until you get to a city water connection at an RV park. But with the puny tank in your PUP, you'll want to get every drop you can into that tank...assuming you are dry camping. You'll know it's full when it won't take any more water...as described in my previous post.

Speaking of dry camping. What do you do if you run out of water in camp? I boondock exclusively, and I'm fond of these: https://smile.amazon.com/Reliance-Pr...s%2C236&sr=8-2
I carry four 4 jugs in the bed of my pickup...28 gallons...240 lbs of payload.

The beauty of the Reliance jug is its cap. The threaded hole in the cap is 1/2" NPT thread...into which you screw their spigot...or not. In my case, I adapted a cap with a 1/2" NPT to 1/2" barb plastic adapter: https://smile.amazon.com/Connector-P...xpY2s9dHJ1ZQ== (buy just one at your local hardware store). To that I added about 15" of clear plastic hose to the barb and held it there with a hose clamp...also at the hardware store.
With this adapter, I can dump a 7 gallon jug of water into the fresh tank in a couple of minutes...WITHOUT SPILLING HALF OF IT!! 7 gallons of water and the jug together weigh 60 pounds...easy enough to handle for someone who is fit. If that seems too heavy, choose a 5 gallon jug (about 45 pounds) https://smile.amazon.com/Reliance-Pr...1018216&sr=8-6 from Reliance that uses the same cap. Get a couple of spare caps. https://smile.amazon.com/Reliance-Pr...1018281&sr=8-7 Given that the caps cost as much as the jugs...just buy more jugs, but at least one cap will be dedicated to your fill adapter.

With the water in my fresh tank and 28 gallons in jugs, I can comfortably go about a week--even with showers. These tanks are also easy to fill at Forest Service campground hydrants, and even at a handpump. The jugs make water a non-issue when boondocking.

Lastly, my jugs last 3 to 4 seasons. The sit in the bed of my truck nonstop from spring until fall...exposed to the brutal UV here at altitude in CO. Sooner or later, the plastic breaks down and the jugs fail. I just get new ones.

Lastly +1: These jugs make sanitizing the fresh tank super easy. I put the right amount of bleach for the whole fresh tank into one jug, fill with water, shake and pour. This ensures adequate dillution of the bleach rather than hoping you get a good mix after pouring straight bleach down the fill pipe.

[JimMorrell]

I really don't understand your problem. For 50 years I have filled my fresh water tank until it starts to come out the overflow. I have a hose attachment with a ball valve so I can shut it off immediately. I NEVER allow pressure to build in the tank. The parts I used to make the hose attachment are readily available at any hardware store. Its not rocket science!

[5picker]

Originally Posted by JimMorrell

I really don't understand your problem. For 50 years I have filled my fresh water tank until it starts to come out the overflow. I have a hose attachment with a ball valve so I can shut it off immediately. I NEVER allow pressure to build in the tank. The parts I used to make the hose attachment are readily available at any hardware store. Its not rocket science!

It isn't rocket science to those of us who have camped 50 years and filled our tanks hundreds of times.

To those newbies who suddenly see water pouring from under ther R/V for the first time, it can be daunting. Couple that with the fact that we see literally thousands of posts where the dealer showed these newbies absolutely nothing.

I believe it is our purpose on this forum to help educate those with little experience.

[JimMorrell]

As I said...its not Rocket Science. Turn the water OFF when you see it begin to come out the overflow. 50 years ago I understood this with my 1st trailer and things have never changed!

[TitanMike]

On my trailer i can hear the water gurgling as it rises in the fill port pipe.

When i hear this I slow the water down to a small trickle.

Works every time.

[dahagen]

My grandson would watch the underside of the RV and say "it's peeing" when the water tank got full.