Can anyone give me info on these portable tanks? I have never used a portable before and have some "overflow" concerns. I would much prefer not having to move my trailer but not sure how well these work. Any advice is appreciated.
Hey jewallc, welcome to the forum. How big is your portable tank and how big is your on-board holding tank. That should answer some of your concerns. I only use the portable tanks for gray water. I personally wouldn't ever mess with transferring my black tank "stuff" to a portable tank. Also, if you are emptying a gray tank I would use an old water hose to do it and not the big sewer hose. That way you can control the amount of flow somewhat.
I have the 25 gal. Barker blue tote, which works very well for both black & Grey water. I check the capacity daily, and disconnect, tote to dump station, dump, rinse and return as necessary. I usually do a separate trip for the blackwater.
Your holding tank sizes will determine the size tote you will need. You wouldn't want to get a tote much smaller than either of your holding tanks.
Having the portable tote allows you freedom to dump when you want to or as needed, (without moving your home) and it takes much less time at the dump station!
Those blue tanks can be pretty effective, if used properly and carefully. There are two different approaches that work well. The first is as mentioned, to only get a size that will hold at least a little more than your larger holding tank. By doing that you can always be sure to be able to fully drain the holding tank into the tote tank. The problem with that is the size of tote tank that you will need. Remember that the waste is mostly water and so will weigh about 8# per gallon or a 40 gallon tank when full will weigh in at about 320#.
Another approach is to use a smaller tank and empty it more often. That is what I do when I use one since I don't want to fool with 300#+ and I have fourty gallon holding tanks. I got one from Thetford and I also got the float level indicator that serews into the vent/hose connection on the end of the tank away from the large sewer hose connection. I then just keep it connected to the gray water tank with the dump valve open. Once that tank level reaches about 3/4 full, I close the dump valve and take the tank to the dump station, I then empty the black tank as well since it does not fill as rapidly as the gray tank and that means that I also have the space to flush the black tank into the blue tote tank as well. Of course, it is still important to watch that level indicator.
I use a twenty gallon tank which serves us well and it fits into the storage area that we have available. By doing that, it means that the most my tank will ever weigh is about 160#, which is as much as I care to fool with.