Waste Water Tanks – Inaccurate Monitor Reading Issues

[HammerToe]

Waste Water Tanks – Inaccurate Monitor Reading Issues

Arguably the single most common complaint from RV owners has to do with inaccurate Waste Water Level Monitor readings, especially after an RV is more than a couple of years old. Most frequently, the complaints seem to involve inaccurate Black Water tank readings but may also, to a lesser degree, involve grey and galley water tanks. Possible/probable causes (such as toilet paper stuck on a sensor, soap scum shorting out probes, etc.), remedies (involving the use of water softening chemicals, detergents, wand flushes, ice cubes, etc. to restore function) and preventative measures have been thoroughly discussed and I will not go into them here.

Rather, I thought I would undertake to document my experiences during my 5 years of ownership of a 2008 Cougar 291RLS and what I think I may have learned that might be NEW in this area in the hope that others might find it helpful to them as well AND to solicit comment.

Fresh Water Tanks:

NOW, maybe I might have ‘missed something’ in the manual and should be appropriately chastised BUT I sort of thought that all one would have to do to fill an empty fresh water tank up for use would be to stick a water hose, using an appropriate fitting that didn’t fit ‘too tightly’ (so that excess water could escape around it when the tank was full) into the RV’s filling tube and turn on
the tap (‘not too hard’).

This, it seems, MAY not be a good method.

Why? I always assumed that as long as excess water could escape around the hose in the filler tube, that was sufficient. However. I started to notice something… After prepping my 5th for towing, hauling it out of my back yard, down the driveway, out onto the street, parking, going back to close a BIG gate, and returning to the trailer, I started noticing water dripping down onto the street near the right, front landing leg/propane tank compartment.

Jeez, I thought, where is THAT coming from.?

Confirming that it was fresh water, I initially thought that maybe I had a leak somewhere in the roof and that water from rain or melted snow might have gotten into a wall cavity and that THAT might be the source…

However, I got down on my knees and inspected the underbelly of the trailer and noticed a ‘Big Sag’ in the underbelly material (forget what the name of this material is at the moment) and thought “that does not look right”.

So, I decided to unhook the 5th from my TV, loosened three hex screws at the front edge of the trailer’s underbelly cover and then ‘knelt’ the front of the 5th down as far it would go by fully retracting the landing gear. The result: a LARGE QUANTITY of water flowed out.

What I concluded was that (‘when you think about it’), the fresh water tank (specifically, at least for now) MUST have a ‘vent to air’ SOMEWHERE to let air IN when the pump draws water out and my conclusion was that, excess water escaping around the filler hose was NOT SUFFICIENT to keep water from being forced out ‘that’ vent pipe/tube and escaping into and pooling in the underbelly cover.

So, (a) what I decided to do and (b) my NEW FWT filling procedure:

The first thing I decided to do was to develop TWO new strategies for filling the FWT (which I would welcome feedback on):

First, in order to (a) maximize the amount of water I thought I could safely put into the FWT without overfilling, (b) CONFIRM the capacity of the tank was ‘as advertised’ and (c) roughly calibrate the monitor gauge, I
a. Drained the FWT completely
b. Hooked up filling line from an outside water tap, ensuring that I had a in-line water shut-off valve as close as possible to where the filler hose entered the trailer’s fill tube,
c. Went downstairs into my basement and read my water meter,
d. Went back outside, opened the in-line valve at the trailer and
e. Went inside the trailer and monitored the monitor gauge AS the tank filled by pressing the test button every 5 seconds or so,
f. As soon as the pressing the test button resulted in a 100% BRIGHT (not dim or flickering) indicator light indicating that the tank was 1/3rd full, I went QUICKLY outside, closed the in-line valve, went down the basement and read the meter.

I repeated this process with the 2nd and 3rd (2/3rds and 3/3rds full) lights.

When the 3/3rds full light was ‘lit’, my household water meter indicated that I had NOT added the maximum amount of water (227L, in this case) that the FWT could theoretically hold per ‘the specs’ so... I went back downstairs one last time and VERY SLOWLY brought the total volume of water added up to 227L and, fingers crossed, went back outside, looked under the trailer and inspected the belly pan and … it looked like… no problem. (No sign of a ‘sag’)

So, insofar as my FWT is concerned, it would seem to appear that:
a. I now know for certain the size of FWT I have
b. I now know (roughly) how many gallons/liters I have in FWT at each monitor reading and
c. I THINK this procedure is/should be ‘safe’ in terms of not overfilling the tank.

On the last point, I’m not POSITIVE!.

SUPPOSEDLY? The last 10% of the tank’s capacity (at 100% full on the gauge) is for (what) safety margin when adding water when filling? Expansion? Other? So (e.g.) does 227L ‘mean’ the tank’s Absolute Maximum Capacity or the AMC LESS 10%. (‘Full’ probes are supposed to be installed as Full less 10%, based on installation instructions I have seen).

Perhaps someone at Keystone/or anyone ELSE who KNOWS can comment.
However, to date, this seems to work without causing (overfilling) problems…

Black, Grey and Galley Tank reading problems….

Aw Yes, Me too. Started ‘acting up’ in year 4 of ownership - some of these tanks, black generally, would give false 2/3rd or 1/3rd full readings after they had been completely drained and flushed.

Until very recently, I managed to get these tank gauges working correctly again using the Widely Know And Discussed Standard Remedies but this last time, all attempts to get the 1/3rd full readings to go out failed. I.e. even ‘after’ using these standard routines and COMPLETELY FILLING, DETERGENTING/SOFTENING/WAND WASHING, etc…AND THEN COMPLETELY DRAINING THESE TANKS…

Crap! What to do? I like things to work the way they’re supposed to.
Anyway, I happened to inspect the underbelly of the trailer again and “what do you KNOW” – another ‘sag’”. But this time the FWT could not have been the source.

I started to wonder… it sure looked like/I strongly suspected it ‘was water’ again –what ELSE could it be?) BUT FROM WHERE? When I had returned from camping, I had drained the remaining water from the FWT so I did not think the FWT could possibly be the problem/source BUT…

I wondered, could it be possible that, regardless of where the water came from, that this water pooled in the belly pan could be shorting out the lowest (1/3rd full) water tank probes ON THE OUTSIDE of the tanks?

Well, I cannot say for certain BUT: I decided: “what the hell?” I carefully drilled a small (1/4”) hole in the lowest point of the underbelly pan and… struck water…(as I expected). Water ran out for some time (small hole, didn’t watch, but maybe 15 minutes or so)

When it had stopped, I ‘rocked the trailer up and down’ using the landing gear and managed to get a bit more water out.

Finally, when I had gotten out as much water as I could using this method, I went inside the trailer, checked ALL the Waste Water Tank levels and ‘voila’ – they ALL (finally) ‘read empty’.

So, where are we?

I cannot/am not prepared to say with 100% confidence that it was ‘eternal probe shorting’ that might have caused these false readings but I suspect it might have.

Conclusions:

1. Comments with respect to ‘precisely’ how much water one should add to a Fresh Water Tank – i.e. a measured quantity equally to the tanks rating – is that ‘SAFE’? Or should one stop at Max less 10%? OR when the monitor reads full? (Many owners would like to ‘go out with’ with as much FW as possible, I would suspect).

2. Where, precisely, are ALL these tanks (Fresh, Grey, Galley and Black) GENERALLY ‘vented’. Is it POSSIBLE when ANY of these tanks are overfilled, water could collect in the underbelly pan? (Especially Black Water Tank water… SOME owners have mentioned that, given inoperative gauges, they wait until they can see the …stuff… through the toilet drain before they dump SOOO…. (will leave this to one’s imagination). In MY CASE – filling the black, grey and galley tanks with FRESH WATER, COMPLETELY until water (in the shower, in this case, would no longer drain and galley through the galley sink and toilet trough the drain): could filling ‘completely’ in this method (have) cause(d) overflow water to pool in the underbelly?

Comments?

In any event, I’m going to run some more experiments, calibrate ALL my 5ths gauges as best I can (using the FWT method above) and confirm their max capacity but I am definitely interested in the Fill to Advertised Max, Advertised Max less 10% or Gauge 100% Full level issue.

Not sure if water pooling in the underbelly pan may or may not cause problems (over and above PERHAPS inaccurate gauge readings) in the long run but I don’t want it there, would like to avoid any possible problems, try and keep the gauges reading correctly if possible and avoid having to drain water out of it repeatedly.

I intend to LEAVE that ¼” hole I drilled open. Nothing much should be able to get up it (IMO), it’s not likely to plug up and any other issues (such as heat loss) should be inconsequential.

Thoughts? Comments? Info?

[f6bits]

1) Coroplast

2) My fill connector has a vent right above the fill hole.

3) AFAIK, your waste tanks shouldn't vent at tank level. My black tank vents to the roof. My grey doesn't vent – it pulls air from the drains through the traps. When my black tank is full, it backs up into the toilet. When my grey tank is full, it backs up into my tub.

4) The fresh water capacity spec includes the contents of your hot water heater.

[Ken / Claudia]

How, thats a investigation. I just fill the tank and check the gauge at times I fill until it overflows out the fill port. The gauges (probes) work most of the time, never had a RV that they always worked. To much stuff can get them dirty. Good luck with the leak, that can be a real pain to track down but, needs to be done.

[jsmith948]

Re: FWT
I believe you could have a leak (crack?) on the top of your tank or your vent hose is leaking. When we fill the FWT on our Cougar, the water will come out of the vent next to the fill port (and the fill port as well), but, does not run into the belly of the trailer. Good luck!

[HammerToe]

Thanks for the responses.

1. Yeah, 'Coroplast' - I remember NOW.

2. 'Ditto' the screened vent hole above the fill hole. I remember that now also; guess I forgot as I've either been careful since I first 'experienced it gushing out' excess water as I now either only fill till either 'FULL' on the tank monitor *OR* (as mentioned) put no more than (in MY CASE) the max of 227L/60USG in the FWT.

3. Thanks for the insight into where the waste water tanks 'get their air from'. Makes sense/should have thought of that.

4. Also - thanks for the insight that the Fresh Water Capacity of an RV does? might? include the Hot Water tank. Looked it up - S/B 6USG/22.7Gal in my case. I'll run a test to confirm that just to be absolutely certain.

I find that final point quite interesting since IF I wish to use the 'Fill FWT by Water Meter Reading from inside the house' method, one would have to take into consideration: "is the HWT empty or not" (e.g. 1st fill of the year after HWT drained for winterization".

I also suspect that MAYBE if one tries to fill the FWT using a hose hooked up to the city water supply, thete MIGHT be a risk that one might 'crack something somewhere' as there would probably be at least SOME pressure build-up somewhere and these tanks aren't really designed (I suspect) to 'take much pressure'.

I think my next step will be to make sure that ALL tanks are empty AND that my HWT is 'off' and drained. THEN will will slowly fill EACH (and ALL) tanks one by one (initially) to 'FULL' on the tank monitor and then 'knell' my 5th down and see what (if anything) might come out. (Hopefully, nothing!).

THEN I will reapeat the tests by adding MORE FW to EACH tank SLOWLY (until can't put any more in) and again see what might come out and 'when' (i.e. try to identify the 'culprit tank'.

AS LONG AS no water ever 'comes out' and pool in the Coroplast by taking care that I NEVER fill the FWT past its FULL reading on the monitor, I will be happy...

(Actaully, now that i've got 'that' 1/4" hole there in the Coroplast, I might be able to skip the 'kneeling' exercise. (Which can be quite useful when waxing the trailer or changing front light bulbs, however...).

Thanks again

[Roller4Tan]

My thoughts... When you first filled your FWT to overflow, did water come out the vent next to the fill? If it did not then the hose became disconnected at the tank (or never was connected), and water is coming out that port and filling up your under belly. Might be worth a look.

[rclark]

Just a thought in regards to the 1/4 inch hole in the Coroplast. I have had to open the Coroplast on my 2004 Everest to replace the hydraulic cylinder. To close it up I used Gorilla Tape and it works perfectly for any repairs to the Coroplast.

[Festus2]

Originally Posted by HammerToe

I also suspect that MAYBE if one tries to fill the FWT using a hose hooked up to the city water supply, thete MIGHT be a risk that one might 'crack something somewhere' as there would probably be at least SOME pressure build-up somewhere and these tanks aren't really designed (I suspect) to 'take much pressure'.

Thanks again

I'm not sure I follow you on this one. If you have a hose which is hooked up to city water at one end and connected to your RV at the other and turn on the tap, the water does not go into the FW tank. It goes directly into the FW lines in the RV and bypasses the FW tank.

As far as I know, the only way to fill your FW tank is to use the potable filler inlet which is located right beside your city water connection. It doesn't seem possible to have too much pressure building up in the tank itself simply by using a filler hose shoved into the potable water inlet. You might end up overfilling the tank but that is all that could happen.

Maybe I misunderstood your comment above. ???

[HammerToe]

Thanks for all the Feedback:

In response to Roller4Tan:

Yes, when I first (and used to) do a fill, water DID come out the overfill vent. Since then (since I started experiencing water pooling on occasion in the underbelly cover), I've been (more) careful to avoid putting too much in so as to avoid that. I MIGHT as a test try a 'SLOW overfill' of the FWT now that there's a hole in the Coroplast just to see if (a) water still comes out the overflow vent 'if appropriate' and (b) as part of an attempt to locate the possible source of the 'water pooling'. One concern I have (as mentioned previously) is that, overflow vent (provision) notwithstanding, filling the FWT at a 'too rapid rate' using a water hose COULD nevertheless result is a/SOME water pressure buildup in the FWT sufficient to possible 'crack something' OR 'pop a hose' somewhere which could, in (the) future (fills), result in (overflow) water pooling as I now experience.

One way or another, I'll find out.

In response to RCLARK: Thanks for the suggestion. As I stated, I'm not (too) worried avoid (even!) leaving a 1/4" hole as (a) heat loss should be absolutely minimal, (b) IN THE EVENT water should get on the upper side of the Coroplast, it will now have a place to drain and (c) nothing is likely to be able to 'get up through it' and/or plug it.

In fact, I think I might even make the hole slightly larger AND insert a small, right-angle fitting with 'the angle' pointing towards the rear of the trailer AND add a short piece of clear vinyl tubing to further minimize the possibility.

In response to Festus2 (and partly answered above): Yes, I am/was aware that 'using the screw hose connection', water would not flow into the FWT as you mentioned. However (and again), I nevertheless think that, the ability of the overflow vent to funnel off excess water notwithstanding, there would necessarily HAVE TO BE SOME pressure buildup in the FWT and I doubt that these 'holding tanks' were designed to take (much) in the way of a pressure buildup and might result (e.g. only) in crack in a seam/weld joint. I'm not CERTAIN but I seem to recall that 'city water pressure' can run as high as 60 PSI or more and 'so' - if the overflow vent were plugged (e.g.), that would result in a 60 PSI buildup if the FWT. NOW - even 'given' (assuming) proper operation of the overflow vent, the pressure in the tank would not (absolutely) be 'ZERO'. There would still have to be SOME (for the water to be forced out.

How MUCH buildup? I don't know, but it is not inconceivable that 'enough' to result in a 'crack' or something in a joint, connection, etc.

Anyway, thanks all, again, for the feedback. If/as I learn something more, will 'add' to this thread.