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Filling Water Tank (Newbie Question)

Hi Everyone!

I have a complete newbie question: I have a 2024 tab 400 and I want to fill the fresh water tank for boondocking, how do I know when it's full? Is there a way to know besides running inside to check the gauge? Currently I'm running back and forth and this seems silly. Surly there's a way to know when it's full from outside the Tab 400, right?

Also... what happens if I overfill the tank? Will I burst the tank? Will it hurt the fixtures?

Thanks in advance!!
Lisa

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    Jay_and_KatJay_and_Kat Member Posts: 228
    Supposedly you'll eventually have a "feel" for when your tank is full.  We've had ours two years and I'm still waiting to get that feeling...

    Now, as for overfilling the tank, there's an overflow drain that will start dumping water if you reach the limit.  The one thing I've read some people can run into is if insects nest in the drain tube, THEN you can overfill the tank causing damage to the camper.
    ----------------------------------------------------------
    Jay and Kat
    Tow vehicle:  2022 Jeep Gladiator Sport S + tow package
    Camper:  2022 T@B 400 Boondock w/Norcold 3-way fridge
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    elbolilloelbolillo Member Posts: 336
    Hi Everyone!

    I have a complete newbie question: I have a 2024 tab 400 and I want to fill the fresh water tank for boondocking, how do I know when it's full? Is there a way to know besides running inside to check the gauge? Currently I'm running back and forth and this seems silly. Surly there's a way to know when it's full from outside the Tab 400, right?

    Also... what happens if I overfill the tank? Will I burst the tank? Will it hurt the fixtures?

    Thanks in advance!!
    Lisa

    Fill it up until it comes out the overflow. No need to run inside and check the gauge. Unless the overflow becomes clogged, you won’t hurt anything. 
    _____________________________________________________
    Ken / 2023 Tab 400 “La Bolita” (20,000+ miles) / 2024 Toyota Sequoia
    2024 - 1 Trip - 20 nights - 3 National Parks, 2 National Forests
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    BaylissBayliss Member Posts: 1,328
    @lisawarninger, here is a discussion about the overflow drain and insects (e.g., mud dauber) blocking the drain, which can ultimately result in major damage.  It also discusses putting screen over drain tubes:

    Don't let this happen to you! Blocked fresh water tank overflow with Nautilus system. (vanillacommunity.com)

    The following discussion shows what can potentially happen if the drain becomes blocked:

    TAB400 freshwater tank repair (vanillacommunity.com)

    As @Jay_and_Kat mentioned, when the tank overflows, water will exit through the overflow vent.  However, you can also monitor the level of water in the tank using the tank monitor inside the trailer.  BUT, keep in mind that the monitor sensors attached to the tank are not always accurate.  My best advice is to not leave the water hose while filling the fresh water tank.  You want to monitor it for any problems during the filling process.  It is unlikely that you will have issues filling the tank, but better safe than sorry.

    Another option you might consider is something I just ordered.  It is inexpensive, so I want to give it a try and see how accurate it is.  If you boy one, however, test it out (e.g., by filling a bucket of water) to see how accurate it is.  There are many versions available, but I opted to purchase this one:

    Diivoo Water Flow Meter with 180° Removable Panel, 4 Measure Modes, ±5% High Accuracy and IP54, Measure Gallon/Liter Consumption and Flow Rate for Outdoor Garden Hose Watering, RV Water Tank Filling


    2019 T@B 320 S Boondock Lite2007 Toyota Tundra 4x4
    (Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePo4; Solar: Renogy 100Ah Suitcase; Victron BMV-712; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
    Greg & Marlene (Tucson, AZ)


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    BinghiBinghi Member Posts: 288
    I used to run back and forth checking the idiot lights inside the trailer when filling the fresh water tank. Problem is, the fourth “Full” light on the display comes on long before the tank actually fills up. Despite my misgivings about the dreaded mud dauber nest drain line clogging phenomenon, I began filling the tank by running the supply hose until water flows from the tank’s overflow drain line. This method has worked fine for me. I figure the more frequently I fill the tank to overflow, the more likely the drain line will remain open.
    2021 400 BD / 2016 VW Touareg / Austin, TX
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    pthomas745pthomas745 Moderator Posts: 3,753
    The little spout under the trailer we describe as an "overflow" is really the vent for the tank.  If I had a trailer with a vent like this, I would be filling the tank and....feeling down under the trailer for air coming from the vent.  No air coming out?  Stop filling the tank until you check the vent.  This simple check will let you know immediately if the vent is blocked, and will prevent the damage we have seen that is noted in the threads above. 
    After you know your vent is clear...then you can use it for an "overflow".  The tank must be venting for the overflow to actually work.
    2017 Outback
    Towed by 2014 Touareg TDi
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    BaylissBayliss Member Posts: 1,328
    Excellent clarification, @pthomas745.
    2019 T@B 320 S Boondock Lite2007 Toyota Tundra 4x4
    (Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePo4; Solar: Renogy 100Ah Suitcase; Victron BMV-712; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
    Greg & Marlene (Tucson, AZ)


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    BaylissBayliss Member Posts: 1,328
    Just to follow up on my earlier post about the "Divoo Water Flow Meter" (see June 10, 2024 post), I received it, and it worked as advertised.  I tested it by filling a 5-gallon bucket of water.  At first, it overfilled the bucket by about .25 gallons, so I adjusted the flow, which is easily done with the digital control.  It has a +/- 5% high flow rate, with an adjustment between -30 and +30.  I got it very close to an accurate readout at 5 gallons, so I called it good.  The next test will be when I pull my trailer out for our next trip and fill the freshwater tank.  I like the meter, and the price point at $10 was a good deal.
    2019 T@B 320 S Boondock Lite2007 Toyota Tundra 4x4
    (Alde: 3020; Refrig: Isotherm Cruise 65 Eleg; Battery: BB 100Ah LiFePo4; Solar: Renogy 100Ah Suitcase; Victron BMV-712; Pwr Cntr: PD-4135KW2B; EMS: PI-HW30C)
    Greg & Marlene (Tucson, AZ)


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    dluckdluck Member Posts: 7
    I have a related newbie question. We're planning to use hot water for the first time and will be boondocking - if I switch the "Bypass" switch over while filling the tank does it fill the water heater tank too? How will I know that it is full, or do I just keep filling until it comes out the overflow vent?
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    pthomas745pthomas745 Moderator Posts: 3,753
    @dluck What year and model trailer? In general, when you are ready to go camping and all the "dewinterizing and sanitizing" processes are done, the trailer should be in "Camping Season" mode.  There can be several different valve positions that need to be correct for "Camping Season" mode to be set, depending on exactly what trailer and what year.   Once those valves or the "bypass handle" are correct, then water can flow to all the appropriate places in the trailer.  The hot water tank will be filled when you open a hot water faucet.
    So, tell us what year and model and we can get more specific.  Same thing with the fresh water fill. 
    2017 Outback
    Towed by 2014 Touareg TDi
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    Sharon_is_SAMSharon_is_SAM Administrator Posts: 9,582
    edited 12:24AM
    @dluck - if you are referring to your 2021 CSS with Nautilus, After filling your fresh tank, then place the Nautilus in Dry Camping mode. Turn on the pump, open a hot tap and the Alde water tank will fill.  You know it is full when the tap no longer sputters.  Be aware, this will draw down the fresh tank by several gallons.  Better to hook up to city water, open a hot tap and fill the Alde tank, then switch over to fill the fresh tank.  Then proceed to Dry Camping mode.
    Sharon / 2017 T@B CSS / 2015 Toyota Sienna Minivan / Westlake, Ohio
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    dluckdluck Member Posts: 7
    Thanks, @Sharon_is_SAM! Yes, it's a 2021 320 CS-S.  I want to start with the fresh tank full for sure so thanks for this helpful advice.  
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    lkc001lkc001 Member Posts: 761
    I also use that little water meter, but I use it on my backflow attachment I use when I dump black tanks so I know how much water I'm backflushing.  Don't use the same meter for filling fresh water.
    2016 Nissan Frontier SV V6 4x4
    Finally!  New Owner of a 2017 Tab 320S! 
    Woohoo!
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    berggerbergger Moderator Posts: 1,072
    For our 400 I fill up the fresh tank until it overflows.  During this process, which takes about 7 minutes with a pressure regulator on our water spigot, I also feel for a flow of air coming out of the vent.  We do not have mud daubers where we live but I am still wary of the vent getting plugged.  I also plan on putting some screen over the vent this summer.  Timing your fresh water tank to fill will let you know when it is getting close to full.  I could always turn my hose off just at the 7 minute mark and it will usually prevent the overflow from happening.  

    After the fresh tank if full I switch over to city water and fill the lines and the Alde tank so I don't waste water out of my fresh tank to do so when I get to camp.  The final step is to turn it back to dry camping mode, turn on the water pump and let a little water out of each fixture just to make sure the pump is primed.  
    2021 T@b 400 BD  "Vixen Gail" 
    2018 Nissan Titan Pro 4X "Big Bird"
    Leadville Colorado
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