Gray water gauge check

[Riwright]

I ran a check on my gray water gauge today. Starting with an empty tank, I dumped two gallons at a time down the sink and checked the gauge after each dump. The tank holds 30 gallons.

Here are the results:

2 gallons -- Reads 1/3 full
4 gallons -- 2/3 full flickers
6 gallons -- Reads 2/3 full
16 gallons -- reads full

I continued to fill the tank. I expected water to back up into the tub but instead I got water leaking out the bottom of the trailer. It was coming out of a black plastic cover near the winterizing valves. Is there a leaky J trap under there that I need to fix?

The water started leaking out the bottom of the trailer at the 30 gallon mark so the capacity is what I thought it was.

I was surprised that the gauge was that far off. I don't think the sensors are fouled. From what I've read a fouled sensor stays stuck in the "on" position when the tank is empty. Mine go on and off when the tank level changes like they should. It's just not accurate.

It's useful to know how the lights match up to what's actually in the tank. I can watch it come up to "full" and know that "full" is really half-full. I'll have to depend on the tub backing up to know when it's really full.

Is the black tank gauge any more accurate? What happens when that thing fills up? Can you see the black water?

[Dave99gst]

I may be wrong -- but i dont think the sensors are installed alll that precisely. I think there location is pretty much just eyeballed and I would assume they do not come pre installed from the manufacture.

[ThePair]

Were you very, very level? The leveling of the TM can drastically affect the accuracy. Plus, I don't think they're accurate at all, I just use them as a very vague guideline.

As to the spillage, I'm thinking there's probably a vent someplace for the tank (I'm fairly sure that a vent is a requirement) and that very sits lower than the bottom of the tub, hence the leaking you are witnessing. I would think that's a good thing, leaking outside the TM rather than inside.

I can't say as I've ever filled the gray tank, so I wouldn't know.

As to the black tank, that's really just the toilet "box", and the float-type gauge in there is either stuck, or works. If it works, it's more accurate that the lights for the gray tank, because it is a simple float. If it's stuck, you can unstick it manually, or via the "Geo Method".

Well your results are interesting! I always thought that our grey water tank readings were screwy. On our unit, the grey water tank is thin, flat and wide. Any slight tilt would throw off the readings. So, personally, I've given up on the sensors.

With the grey water tank I just dump it every few days into my caddy and take that to the dump site. We know our usage pretty well by now so this works ok.

And when we put in a new 30g black tank (the Elkmont has a regular non-recirculating Thetford RV toilet), I didn't put the sensors back in as they never worked well before, despite all our cleaning and flushing.

But I can now turn off the flush water and peek into toilet with the flashlight and see how full the tank is. When full, time to move the trailer to the dump site - I don't use a caddy for black water, yuck.

[MudDog]

Originally Posted by ThePair

As to the spillage, I'm thinking there's probably a vent someplace for the tank (I'm fairly sure that a vent is a requirement) and that very sits lower than the bottom of the tub, hence the leaking you are witnessing. I would think that's a good thing, leaking outside the TM rather than inside.

I can't say as I've ever filled the gray tank, so I wouldn't know.

If there is a vent lower than the tub (I would think any vent would have to be higher), my TM doesn't have one. In our first 10 trips we were in the Santa Cruz Mountains at a site with water and electric.

We left for much of the day and returned to a TM with a full gray tank and a tub about 1" for flowing over. We had left the city water faucet on (with a pressure regulator), and an o-ring on the tub faucet had failed causing a leak. The leak filled the gray tank and then started filling the tub. Had we been 15 minutes later the floor of the TM would have been flooded. There was no sign of water outside. We didn't have sewer hook-ups, so had to drain some water into buckets (before my blue tote) to get the water level down in the tub enough to pop the trailer down and visit the dump station.

Once back at the site I took the faucet apart and re-seated the o-ring and the leak stopped.

Now when we leave the campground, we turn off the city water.

[Bill]

The gray water tank is supposed to back up into the tub. Unfortunately, there was a period of time in which the inlet plumbing at the top of the tank was not fully glued when everything was installed. In those cases, when the tank gets very full, the water seeps through the unglued joint at the top of the tank, and out onto the ground, rather than into the tub. Since it is grey water, not black, it is not a disaster, but it is still not a good situation. To make things worse, the leaky joint is not accessible for repair.

As has been noted, in order to fit under the trailer, the grey tank is big and flat and very shallow (only a few inches deep). Putting water in it is like putting water on a cookie sheet - even a small tilt will change the level of the water against the sidewalls. That is why the sensors are kind of squirrely. I think this is true in most trailers. This is unlike the Thetford black tank, in which the tank's length, width, and depth are all more or less the same, and the level gauge is a straight-line mechanical float.

Bill

[T and C]

I have experienced the grey tank overflow problem on two occassions. It shows up as a slow drip. I suspect I must have one of those tanks with the connection that was not glued. My TM is an '08 3023.

On both occassions draining the tank stopped the drip. Last time my wife and I had been in that particular campground for 5 nights w/o draining it.

Tom

[ELM-JLM]

I continued to fill the tank. I expected water to back up into the tub but instead I got water leaking out the bottom of the trailer. It was coming out of a black plastic cover near the winterizing valves. Is there a leaky J trap under there that I need to fix?

Hi RI,
If the leak is inside a black box with a circular screen at the bottom it is a loose tub drain trap! I had leakage while the shower was being used! It was simple to repair! A few screws and the box was off. The plastic round tightener had a crack from overtightening I assumed! Its the same trap you can buy in Lowe's or Home Depot! I had some plumbing parts in a drawer and was able to snap a new ring on the trap and retighten!

[Riwright]

>>Were you very, very level? The leveling of the TM can drastically affect the accuracy. Plus, I don't think they're accurate at all, I just use them as a very vague guideline.

No, not really. I tested it on the lot where I store the trailer so it wasn't really leveled properly.

>>*If the leak is inside a black box with a circular screen at the bottom it is a loose tub drain trap! I had leakage while the shower was being used! It was simple to repair! A few screws and the box was off. The plastic round tightener had a crack from overtightening I assumed! Its the same trap you can buy in Lowe's or Home Depot! I had some plumbing parts in a drawer and was able to snap a new ring on the trap and retighten!

Yes, that sounds like it. I couldn't get a really good look at (it was dark). I'll have another go at it when I have some daylight. If it's a trap then it's an easy fix.

I think if I can get the gray water to back up into the tub then that will be a happy thing. The most important thing I need to know about my gray water level is when it is full. And I need to find out in some non-destructive way (tub fills up, grey tank overflows onto the ground). Having it back up somewhere in the trailer is not what I want.

Come to think of it I had a situation where the shower head was dripping into the tub. The carpet in the hallway got a little damp and I never understood how that happened. Possibly it was coming from the leaky trap?

Just an idea, but I wonder if you could add an overflow tube to the top of the grey water tank? You could put a bucket under it and keep an eye on it when you thought your tank was getting full. A little better than having it back up into the tub. Also if you had a big leak it would give the water an emergency escape path. You would be draining gray water onto the ground but if there is a real leak then the water drains onto the ground in any case, it's just a matter of whether it travels through your trailer first.

[ELM-JLM]

If you look behind the rear bumper you can see the sensors! They appear to just screw in! I would think you could raise the full to a higher level and plug the hole with a pvc plug!