Grey Water Tank capacity

[cw1001!]

I went camping this last weekend and my Grey Water Tank filled up faster than I thought it would. This is a new camper to me and I know it has been well used in the past.

When I got home I decided to "measure" how many gallons my tank was by dumping a measured amount of water in the tank. I measured a gallon of water and started filling he tank. I got to 22 gallons and notice it the sink draining slow. Got to 23 and that's all she wrote. My tank specs are supposed to b 28 gallons.

So the question of the day is, do y'all think it is possible that there is that much grease in the bottom of the tank taking up the extra room?

[flybouy]

Was the camper level when you did your test? I would think enough grease or other debris to take up 5 gal worth of space would partially block the drain. How well does the tank drain?

[Balvar24]

How dingy is the water that came out when you dumped the grey tank? If you filled it with clean water and it was fairly clear coming out, maybe not that much gunk?

How level was the trailer mounted? Some models have wide and shallow tanks, so any incline could decrease your capacity by a good bit.

[travelin texans]

I went camping this last weekend and my Grey Water Tank filled up faster than I thought it would. This is a new camper to me and I know it has been well used in the past.

When I got home I decided to "measure" how many gallons my tank was by dumping a measured amount of water in the tank. I measured a gallon of water and started filling he tank. I got to 22 gallons and notice it the sink draining slow. Got to 23 and that's all she wrote. My tank specs are supposed to b 28 gallons.

So the question of the day is, do y'all think it is possible that there is that much grease in the bottom of the tank taking up the extra room?

That's entirely possible. Most of the specs in any rv brochure are/will be off by a little & most by a lot. I doubt it's got 6 gallons of grease, but due to the tank designs it's very difficult to completely drain the tanks.
Don't believe any of the weights posted in brochures for RVs or trucks.
On a short 22' RV there's not room for very large holding tanks.

[cw1001!]

Was the camper level when you did your test? I would think enough grease or other debris to take up 5 gal worth of space would partially block the drain. How well does the tank drain?

The trailer was level when I did my test. It seems to drain well.

[cw1001!]

How dingy is the water that came out when you dumped the grey tank? If you filled it with clean water and it was fairly clear coming out, maybe not that much gunk?

How level was the trailer mounted? Some models have wide and shallow tanks, so any incline could decrease your capacity by a good bit.

The color of the water was pretty normal from what I am use to seeing with my past campers. The trailer was perfectly level. I have a very level spot at my house to park the camper on and it was level at the camp site.

I am thinking if there is grease in there, it maybe old and hardened so it wouldn't show up in the water when I dump it.

I am asking opinions here to see if is worth my effort to try to clean it as that could be a bit of a pain to do.

[cw1001!]

That's entirely possible. Most of the specs in any rv brochure are/will be off by a little & most by a lot. I doubt it's got 6 gallons of grease, but due to the tank designs it's very difficult to completely drain the tanks.
Don't believe any of the weights posted in brochures for RVs or trucks.
On a short 22' RV there's not room for very large holding tanks.

I originally calculated the tank size the weight specs on the side of the trailer. The calculations comes out to be 56 gallons for the tow tanks total. Then I found the specs online and they also said 28 gallons a piece.

[JRTJH]

I don't think you're facing a "extremely dirty gray tank, filled with so much foreign material that it's affecting the ability to hold the rated amount of water...

What I think you're facing is more along the lines of "trailer structural components not allowing the tank to "bulge out" to maximum capacity....

Think about a balloon that is supposed to hold 1 cuft of air. You can almost always get an extra few cubic inches in it as it stretches and expands... But, put that balloon in a half cubic foot plastic box and no matter how much air you try to push into it, it'll only expand to half it's "rated capacity"....

Same with your trailer gray tank. If it's "squeezed in between the floor above it, the cross rails (front and rear) and the support braces below it, if any of them are "too close or too tight", then the tank can't expand and bulge to capacity....

I'd guess that's closer to your problem than some contaminate inside the tank....

Oh, and when you start measuring your fresh water tank and find that it's about 7 gallons too small when compared to the brochure, remember that the 6 gallons of water in the water heater is also "considered fresh water by Keystone".... So, all fresh water capacity ratings are larger than the actual fresh water tank based on the size of the water heater, that could mean up to around 12 gallons....

Brochures and ratings. It ain't just the vehicle manufacturers who use "cute tricks to fool the consumer".... Tow ratings, horsepower/torque curves, fresh water capacity, holding tank capacity and yes, even axle capacity/GVWR ratings are all subject to a bit of "sleight of hand" in the brochures, all covered by that phrase on the back of the brochure in very small print: The manufacturer reserves the right to make production changes without notice".....

[Scttw]

John, you've always had a knack for "Painting a picture" to help folks understand. Well done!

[notanlines]

This might be a stretch, but if the inlet pipe is protruding deep at all from the top of the tank, every inch extra will mean a loss of about 3.5 gallons of water in a 18x46x8 tank. Just a thought. But I sincerely doubt 6 gallons of sludge in the bottom.

[cw1001!]

This might be a stretch, but if the inlet pipe is protruding deep at all from the top of the tank, every inch extra will mean a loss of about 3.5 gallons of water in a 18x46x8 tank. Just a thought. But I sincerely doubt 6 gallons of sludge in the bottom.

That thought crossed my mind. I think the only way I could possibly find that out is use a scope the tank with a camera.

I wish that had access covers on the top of these tanks but of course that would probably cause more issues of dealing with the tank cover and leaks.