A question about holding tanks

[jdarwin]

The DW wants to know how often you empty and flush your black and gray tanks. Also why not just leave all the valves open and just let everything drain.

[L0veless]

your black tank need all the liquid to push everything out your tank and through your hose. IF you don't have enough liquid to clean out the hose and tank you will end up with the dreaded pyramid of poop in the tank and a lot of problems. then I use the grey tanks to finish flushing out my hose after I empty the black tank. there are a lot of posts covering this action.

[AZ Traveler]

John,

Keep your black valve closed and dump about once a week for the reason Loveless highlighted. You can keep grey valves open until a day prior to black dump and to get some water in them to flush the lines after the black dump.

[DQDick]

What happens if you leave the black tank open is that the TP and poop pile up from the bottom of the tank and the liquids drain out around them. As the pile begins to harden you eventually can't flush the toilet because it's reached the pipe going into the tank. Professional help can be required if it gets bad enough, but even without needing professional help it's something folks only do once.

[RMcNeal]

When at a campsite for extended times, I have left the grey tanks open to drain. It was explained to me that when you do that, you can allow sewer gases from the sewer/septic system back into your rig through the open port. I stopped doing that when we experienced bad smells. Now I just dump them about once a week using the grey to help back flush the black.

[DutchmenSport]

Yes, keep them closed for all the reasons posted above.

As to the question, "How often?", that depends upon the size of your tanks and how much water you use. The important thing here is, to dump the black tank when you have sufficient water to help drain as much as possible. The more you have available, the better the black tank drains and flushes out.

Some folks can extend their "dumps" for a week, others may have to dump every day, or every other day. If you have a family of 6, or camping with friends and extra kids, your tank will fill much faster. If you are completely alone, of course, the usage is much less and you don't have to dump as often.

I have learned, when camping for extended stays, I need to dump every two days. We camp at State Parks and they almost never have full hook ups. I use a Barker Blue Tote to dump and hall my waste to the dump station. And the reason I do it every 2 days is because that's how much my Blue Tote will hold without spilling over when I dump all 3 tanks.

But, you say, your black tank is not full. Absolutely correct. I ALWAYS back flush my grey shower water into my black tank to help clean it out. And when back flushing from the grey tank, the process always pulls out more TP and "stuff" that has stuck behind from the first dump (even if the black tank was completely full, it still leaves "stuff" in there. Back flushing helps pull the remaining "stuff" out without having to use any extra water that what has already been used.)

If you back flush, you don't have to have a full black tank when you initially dump. BUT you do need water to help rinse the tank coming from somewhere. If that means adding water again via the toilet, a back flush, or your black tank flush system, the first, second, and third "back flush" will pull so much more "out" of the tank, you'll be shock at how much was left behind from the initial dump. If you get a clear section of sewer hose pipe, you can see what's coming out. Believe me, it's well worth $5 for a clear section. Once you actually see what's coming out, you'll be flushing that black tank as much as possible.

I'll not go into the process of how I back flush. The process is very simple, but explaining it with words is long.