How Often Do You Dump the Black?

[KJRitchie]

We've just taken ownership of a 2008 Classic 25FB and the black tank is enormous compared to our 15 gallon Casita black tank. Normally after a two day state park camping weekend we dump the black then the grey Casita tanks but the Airstream has a 37 or 39 gallon black tank. I would hate to waste so much tank chemicals. One bottle for 40 gallons but if the tank is barely full it seems a waste to dump it. Typically we go out once a month then take the normal 2 to 3 week vacation. If you are going just for an overnight or a weekend trip do you just put in enough chemical for about 20 gallon and then dump the black or if you know you are dumping in a couple of days don't bother with chemicals

If you are on the road do you just dump the black after 3 or 4 days or useage? The sloshing should be helpfull break up the solids.

We don't have the same issue with the gray because the Casita has 32 gallon gray tank while the Airstream only has 37 gallons.

Thanks for your insight.

Kelvin

[overlander63]

The deodorizer part of the chemical stops working after a few days. Dumping it about once a week would be as seldom as I would want to go.

[DKB_SATX]

Ah, modern problems. Since I only have a tiny black tank in the Argosy (12 gallons or so) it never occurred to me to think in terms of big-honking-tank decisions. I dump the tank after every trip, which is usually 2-4 days. I use the "BioActive" enzyme stuff, and just use a few ounces because I know we're not going to fill even the small tank Friday-Sunday. I wouldn't want to store it without emptying the tanks, but considering the likely shape of your under-floor tanks, you'd probably want to run the tank-flush sprayer every time at the end of short trips.

[timmaah]

We don't use any additives of chemicals in the tanks and try to dump as often as we can.

Only had a smell when we first started out and right after we dumped each time. Adding a gallon of water was enough to make it stop. It was hot then (mid 90s) and our tanks hadn't been used in a long time.

Right now it is day 9 since dumping. I'm hoping to make it two weeks, but I doubt we will make it.

[idroba]

I live in a relatively cool climate, and almost never use chemicals in my black tank. I do have a small tank like DKB's but I usually can go a week without dumping (single here). If I do detect odors and it is hot, I add some chemical if the tank is partly full and it is not convenient to dump. That has always killed the odor, even added to a partly full tank.

I would try to dump the black tank about once a week, no matter how full it was, or what size it is, especially if you go sans chemicals.

[Jammer]

Originally Posted by KJRitchie

We've just taken ownership of a 2008 Classic 25FB and the black tank is enormous compared to our 15 gallon Casita black tank. Normally after a two day state park camping weekend we dump the black then the grey Casita tanks but the Airstream has a 37 or 39 gallon black tank. I would hate to waste so much tank chemicals. One bottle for 40 gallons but if the tank is barely full it seems a waste to dump it. Typically we go out once a month then take the normal 2 to 3 week vacation. If you are going just for an overnight or a weekend trip do you just put in enough chemical for about 20 gallon and then dump the black or if you know you are dumping in a couple of days don't bother with chemicals

You'll find that opinions vary widely on the use of holding tank chemicals.

I use aqua-kem liquid, and use a 6 oz bottle after dumping the tank. It's not expensive and I prefer to use an entire bottle at once to avoid problems with spills.

I believe that the environmental problems with aqua-kem and similar products have been greatly exaggerated. Essentially similar products are widely used in the portable toilets for construction and special events, and by airlines.

If you are on the road do you just dump the black after 3 or 4 days or useage? The sloshing should be helpfull break up the solids.

We typically dump tanks when leaving a campground unless there either is no dump site or we're in a big hurry. I dump both tanks unless the toilet has hardly been used.

[MrUKToad]

Being weekend campers, we've always dumped after a maximum of three or four nights, using something called RV Boss as an additive to keep things under control. RV Boss requires a 30 milliliter dose after each dump and that's normally good for that three or four days. We've never had an odour issue and the RV Boss, combined with the dishwashing water which usually gets put into the black tank as well, seems to reduce the waste to a brown soup almost immediately (I often check to see what's coming out of the slinky!).

That said, we've been using the Airstream on the driveway for about five weeks now, during some home renovation, but making a point of using the toilet lightly. It was only this week that I did notice an odour, so I ran down to the nearest dump station; the trailer now smells as it should, especially as I added some more dishwater and a dose of RV Boss. I may not leave it so long in the future!

[TBRich]

We normally dump after every trip, even if it's only a long weekend. However, if we are on a longer or multi-legged trip, we only dump when the black tank is at least 3/4 full. (Frankly, more often than not our dumping schedule is determined by the need to dump the grey tank. If we have to dump one, we go ahead and dump both.) After dumping, we put about 2 gals of water in the black tank and add the chemicals at that point.

As long as there is sufficient liquid in the black tank it's OK to let it stay there between trips ... if they are fairly frequent, but if the AS is not being used for several weeks, it's safer to go ahead and dump. What you want to avoid is solids building up in the bottom of the tank and drying out.

Also, your climate is a consideration. Odors will be more of an issue in warmer climates, and rather than let stuff sit there and "percolate" in the heat, we'd just as soon get rid of it. Also, hot climates may require more chemicals.

[Protagonist]

Originally Posted by MrUKToad

That said, we've been using the Airstream on the driveway for about five weeks now, during some home renovation, but making a point of using the toilet lightly. It was only this week that I did notice an odour, so I ran down to the nearest dump station; the trailer now smells as it should, especially as I added some more dishwater and a dose of RV Boss.

Rather than run down to the dump station, do you have a sewer cleanout plug at home that's accessible? Some places do; others have the cleanout plugs buried. If you have an accessible cleanout plug, then you have a dump station right there at home. That's all a dump station really is, a sewer cleanout plug that's accessible, with a hose alongside for rinsing a slinky.

Anyway, to answer KJRitchie's question, I dump my black tank on two schedules: (1) when the tank level monitor shows it's nearly full; (2) at the end of the trip whether it's full or not. To help control odors, after dumping the black tank, I generally use the tank flush fitting to refill it— right there at the dump station— with clean water, and then dump it again. THEN I dump the gray tank.

Especially during hurricane season, when my Airstream is my escape vehicle for evacuations, I make a point of storing it with completely empty gray and black tanks in case of an unscheduled boondocking opportunity when a storm is coming my way and I'm getting out of Dodge.

[MrUKToad]

Originally Posted by Protagonist

Rather than run down to the dump station, do you have a sewer cleanout plug at home that's accessible? Some places do; others have the cleanout plugs buried. If you have an accessible cleanout plug, then you have a dump station right there at home. That's all a dump station really is, a sewer cleanout plug that's accessible, with a hose alongside for rinsing a slinky.

Sadly, no. There's no sewer access at all, even in the street; if it ever backs up (and they do), it'll all have to be dug up in the front yard, which is something you see quite often in our neighbourhood. If that ever happens then I'll pay to have someone put a discharge pipe in.

[wheel interested]

It's good to dump a full tank to get full flushing power so when we can dump we fill the toilet as full as we can by flushing it until it fills fuller and then empty it. We always add chemicals for a full tank but even that can be adjusted. Warmer weather or longer holding times require additional chemical for the sweet smelling effect.

[Protagonist]

Originally Posted by MrUKToad

Sadly, no. There's no sewer access at all, even in the street; if it ever backs up (and they do), it'll all have to be dug up in the front yard, which is something you see quite often in our neighbourhood. If that ever happens then I'll pay to have someone put a discharge pipe in.

And when you do, you shouldn't ever need to dig up your front yard again, because you'll be able to use the discharge pipe for Roto-Rooter access for any future clogs. Win-win, in my book.

[jcanavera]

The key is having enough liquid in the tank to carry the solids out of the tank. Typically with my 39 gallon tank in our Classic, we typically dump around day 5 if we aren't constantly on the move. The hotter the weather, the more ripe the tank will get as the waste gets cooking. If we are on a weekend trip, I will add water to get the tank to a minimum of 3/4 full and then dump before heading for home. I have no facilities at home to dump the tank.

We use non formaldehyde tank additives to help digest the waste and keep the odor down. We also have a spray cleaner built into the tank and will use it to flush out the tank a few times a year when camped at a full hookup site.

Jack

[A W Warn]

I dump the black at the end of each trip, each time I leave a campground with a dump station, or when the tank is close to full, which ever comes first. When I am set up for longer than a week with hookups, I dump black followed by grey every 3-4 days. I never leave any liquid in any tank when the trailer is not in use.

I occasionally, only when the weather is warm, use a small bottle of chemical in the black tank if I'm going to be in one spot for longer than 3-4 days without hookups. I never use chemical when the weather is cool or when I have hookups.

[handn]

Our favorite place to boondock is 35 miles away from the nearest dump. Two of us make it a week on our 40 gallon tank. We could go another couple of days but don't want to push our luck.
We are careful with our grey water and can make it almost as long before that fills also.
Our water tank is 40 gallons and lasts only 3-4 days. We carry water in jerry cans.
Like others have said, the chemicals lose effectiveness after three or four days and we add more.
We use Oderlos. They are supposed to be environmentally friendly unlike the formaldehyde based chemicals we used to use.

[KJRitchie]

Thanks for everyone's comments.

When I shop for chemicals they all seem to be biodegradable. I have the Camco orange scented bottles, 1 per 40 gallons. I only used half as I figured on our first trip we would only have 10 to 20 gallons of flush. However, our trip was cut short by a malfunction and the trailer is in the shop. We didn't dump before leaving. Hope to get it back Saturday and then I'll dump at our storage site. I'll try out the black flush.

Question about the black flush. I've never had this feature in my past RVs. I found the manufacturers card in the Airstream bag. It mentions not using the hose that you hook it up to for any other purpose. Can sewage get back flushed into the hose? Does everyone carry a hose specific for this task?

Thanks

Kelvin

[Protagonist]

Originally Posted by KJRitchie

Thanks for everyone's comments.

When I shop for chemicals they all seem to be biodegradable. I have the Camco orange scented bottles, 1 per 40 gallons. I only used half as I figured on our first trip we would only have 10 to 20 gallons of flush. However, our trip was cut short by a malfunction and the trailer is in the shop. We didn't dump before leaving. Hope to get it back Saturday and then I'll dump at our storage site. I'll try out the black flush.

Question about the black flush. I've never had this feature in my past RVs. I found the manufacturers card in the Airstream bag. It mentions not using the hose that you hook it up to for any other purpose. Can sewage get back flushed into the hose? Does everyone carry a hose specific for this task?

Thanks

Kelvin

My black tank flush fitting has a check valve in the line to prevent backflow.

However, it's still good practice to never hook up your blue-and-white (or all-blue self-coiling) freshwater line to anything but a potable water source and your fresh tank. Once it has been hooked to anything else, its sanitation is suspect forever after.

[ROBERT CROSS]

We also flush at home thru the clean-out access.
If the tank is partially full I'll flush it with a section of dedicated hose 'til at least 3/4+ full. The trip home usually breaks things up pretty well.

A 1/2 cup of Dawn and a packet of Calgon powdered water softener at Spring get ready helps keep things working. I've done this complete Eco Method once four years ago and followed up with my Spring method with very good results...ie, the monitors are still working.

Bob

[mandolindave]

Bottom line don't use chemicals even if you don't care about the environment.
My friend used chemicals in her motor home. I used enzymes. I dumped both.
Hers had clumps of tissue and # 2 ( but it was a nice shade of blue chemical, and smelled like #2 and chemicals ) Mine was all brown fluid and didn't smell as bad. Mine dumped easier.
Enzymes eat the bad bacteria that smells. You don't have to totally wash your tank as the method calls for giving the enzymes some " food " Sometimes I use Ridex which is very economical.
If you ever have a little spill, micro organiams in dirt will eat the bad stuff before it can travel anywhere. Just as micro organisms eat the millions of pounds of rubber coming off of millions of tires. Not so with blue chemicals and perfume. A guy running a Honey Dipper truck had a bad spill next to my camper. I was furious. It smelled really bad. He said not to worry. He watered the spill down . It soaked into the ground and 20 minutes later no smell. The spill was from my buddies camper who uses no treatment at all.
But to answer YOUR real question. Urine is sterile for 20 minutes or so, then it gets nasty. so dump as soon as you can.
Oh yeah, I forgot Don't use chemicals!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[mandolindave]

Depending on your sink usage...Grey water can get very nasty as well. I use Ridex for the sink and shower. ( and it keeps the pipes from getting build up )

One of the reasons for studying history is so that we can benefit from our mistakes and successes. My thinking is that a whole lot of little efforts can add up to a big difference.