Black tank odor - switch to macerating toilet?

[belfert]

I am having serious problems with black tank odor.  I travel with a bunch of friends and they tend to only open the flush valve the absolute minimum to keep the odor to a minimum.  I replaced the entire flush mechanism on the toilet last year or the year before because it wasn't holding water.  The flush valve is not holding water again and I suspect it is because people are not holding the valve open long enough and getting tissue caught in the valve mechanism.  Replacing the valve is a major project.

One of the options I am looking at is a macerating toilet.  The Dometic 7640 is the best macerating toilet I have found because it will dump through the existing toilet connection and it has a low water use mode.  The issue with the low water use mode is it leaves no water in the bowl.  It also still uses twice as much water as an RV toilet.  With seven people using the toilet that can be a lot of extra water use.

My vent has four or five 90s in it so maybe it isn't venting well because of that.  I use a Cyclone vent cap that is supposed to help pull out odors.  I know some vent with flexible hose out the wheel wheel or similar, but would that just create odor issues at ground level?

Thoughts/opinions/whatever?

[richard5933]

Is the problem while on the road or while parked?

We have a problem with odor if someone flushes while the bus is on the road. I'm guessing that a combination of a low-pressure situation inside the coach and air being forced into our vent as we move. No problem for us once we're stationary with the OTR HVAC system off.

If you're having a problem when the bus is parked, then look at your venting to see if it is clear all the way to the roof. The 90-degree bends aren't helping, but you may also have a blockage caused by a wasp nest or bird nest.

If your valve is holding water, then it's not the problem. Also not the problem if the odor is only there when you flush.

I've also found that if there is a lot of build up above the water line it can cause an odor problem. In this case flushing the tank does improve things some.

Are the people you're traveling with all men? If so, have you given though to installing a small urinal which feeds into tank through a duckbill valve? It would save on water and reduce the number of times the flush valve needs to be opened.

[buswarrior]

The boat peeps have an expert.

"The Headmistress" Peggie Hall has a book on these matters.

https://www.amazon.ca/New-Get-Rid-Boat-Odors-ebook/dp/B01BW2ZSTW

Basically, lack of oxygen is what makes bad stink. Proper venting is EVERYTHING.

Good oxygen, good bacteria do their job without stink.

No oxygen, bad bacteria do their job with lots of stink.

Chemicals kill them both, and leave you with another unpleasant stink, besides the perfume...

After the extensive testimonials on boat forums, extolling the dramatic changes in boats, after upgrading to Peggie's strategies, I will have 2 large vent lines on the waste tank in my new bus to promote good air exchange.

Happy coaching!
Buswarrior

[Gary Hatt - Publisher BCM]

I have a Dometic macerator toilet.  A few comments.

They do allow a little bit of water in the bottom of the toilet after flushing.  Sufficient enuf to keep any stink out.  And you can add more before you leave it if you want.

They do take more water to flush.  The water delivery (side cleaning) is not as good as some other toilets, if you put TP in the bowl, you always have to allow extra water in the bowl, until the paper floats, to basically unstick it from the sides of the bowl.  This can take up to twice as much water as a good flushing drop toilet. Unless you use a toilet brush to push the paper into the water.  If it is not in the water, it will not flush.

These tend to leave some "processed" food particles floating in the bottom of the toilet at all times.  This can be prevented, again, by flushing the toilet up to 20 seconds or so to grind it up and flush it all down.  A good drop toilet does not have the pump in the way impeding everything from going down.

If you put ANYTHING down these toilets, it will have problems. One time I removed a gum wrapper out of my impeller after letting an employee use it.

If/when your pump stops working, a replacement pump is about $350. It is an easy replacement but does take an hour or so.  I am on my second one.

The advantage of a macerator potty is that there will be zero build-up of solids in your tank.  Your tank will flush nicely and you can leave both your black and grey water tank open all of the time. This may be advantageous if you plan to be in a location for a long time and don't want to bother emptying out your tank very often.

I recommend using a macerator toilet only if you have to either pump your waste uphill, or if your black water tank is not in a position either directly under your potty, or close enuf for the wast to flow thru your black water pipe sufficiently.  You can go 3" with very little slope and will be fine as long as you listen for the plop to ensure everything has exited the horizontal (or almost horizontal) drain pipe.

I have had my macerator potty for about 5 years now, I am on my second pump, and it never flushes 100% and my bus still stinks, especially after dumping my tanks and starting out down the road.  So I do not believe using a macerator potty will solve the stink problem, but I am sure a lot of other people can suggest solutions for that, such as ensuring your tank is properly vented, and maybe putting a solar fan on your roof on top of your stink pipe etc.

Good luck.

[buswarrior]

Flushing while underway...

The stock HVAC should be pressuring the coach, not depressurizing it.

An open window or roof vent will defeat the HVAC and create negative pressure to suck toilet gas into the coach.

If the tank vent is in the breeze, change the cut on the top to make it suction at highway speed, nothing will stop a pressurised tank from blowing into the coach when the trap is opened.

If it can't be used "normally"...

More S H I T that the riders are forced to deal with? LOL

The Busnut doesn't have to endure this particular irritant, because he's always stopped when it's time to pee...

Beat that damned toilet into submission. It's yours, and you are it's Master.

Happy coaching!
Buswarrior

[TomC]

One simple thing that should be done with a gravity ball valve toilet. When mine stops holding water, I simply take a round toilet brush and brush out the ball valve opening. It doesn't ruin the seal, and after that the ball seals properly. I don't want the hassle of up keep of a macerator toilet. Good Luck, TomC

[DoubleEagle]

Another angle to this problem is using a conventional toilet instead of the RV style. There are many low water flush models out now that would probably compete with the water used in a macerator setup. The cost is in the $200 plus range, and they would be more home-like. I am heavily considering one for my next redo.

[Gary Hatt - Publisher BCM]

I have had many toilets in the 20 years I have been in the RV world, and 15 years of full-timing.  Most seem to last only 2-3 years in full-time use.  As TomC noted, the round ball type valves do tend to stay cleaner and are easier to clean, but I do not like the looks of them as well as the slide-type.  The slide-type do tend to clog up more. The slide mechanism should be cleaned regularly with a toilet brush but the design is not really suitable for a potty in the first place. Once they stop holding water, they start letting gasses escape and stink up your house. I have found they need to be replaced every couple of years of full-timing, but the last time I did that, the cable broke shortly after that and I bought a new potty. After that, I decided it was not worth fixing a toilet, now I just go out and buy a new one.  Drop type toilets even with porcelain bowls are not that expensive and frequently on sale and then you don't have to worry about it for another couple of years.

Not sure about you but every time my potty broke, It was after hours or on a weekend and it was very inconvenient to get to an RV store, so I reduce the chances of that happening buy just replacing them when they start to act up now.  Thankfully my macerator potty has lasted longer than any of them but at $1000 a pop, they had better.

[belfert]

I have a Thetford Aria Classic toilet with a slide valve, not a ball valve.  I am considering getting the Dometic Sealand 510 simply because it has a ball valve.  It sounds like macerating is not a good idea.  Drop is direct into the tank.

My stock HVAC is long gone.  We use rooftop A/C and don't typically open any windows.  I have a Cyclone vent cover that is sorta like a weather vane and turns whichever way the wind is blowing.

With seven people it is impossible to stop every time someone needs to use the bathroom.  One of the reasons to get a bus was to reduce the food and restroom stops to a minimum.  It was wasting a lot of time when every stop took a minimum of 30 minutes by the time everyone was rounded back up.  I am pretty sure I don't have room for a urinal plus don't they use a lot of water?

Thanks for the responses so far.

[belfert]

The boat peeps have an expert.

"The Headmistress" Peggie Hall has a book on these matters.

https://www.amazon.ca/New-Get-Rid-Boat-Odors-ebook/dp/B01BW2ZSTW

Thanks much.  I got the Kindle version of this book from Amazon and will read it on my iPad on my transit bus ride home tonight.

[Lin]

If there is no water in the bowl, it seems it is always possible to get some odor.  The worst odor comes, as mentioned, from the anaerobic bacteria, so air flow can be very important.  If the bus has been sitting for a while, that bacteria can develop even if there is airflow when you start to move.  We use some septic tank enzyme as a tank treatment.  It's very cheap and seems to help.

The ball valve on our toilet does not always seal properly on its own.  However, if you lift up on the pedal, which adds water to the bowl, it also closes the valve more securely.  I find that I have to clean and lube the gasket every now and then.  One must be careful though to not use a lube that damages the gasket.

[Gary Hatt - Publisher BCM]

If all else fails, this should solve your problem.   

[Scott & Heather]

Don,

With all due respect:

We installed an efficient house toilet in our last bus. Yes we loved it. Absolutely. But no, it cannot compete with the water usage of a gravity toilet. No contest. We would fill a 100 black tank in very short order when underway. I absolutely do NOT recommend a house toilet if you want your fresh tank and black tank to last more than a few days. Trust me on this.

[chessie4905]

4 or 5 90's is the same as no vent. You need to vent it straight through the roof. Rv's and travel trailers figured this out several years ago. It's not the valve closing properly or not holding water. Go look at a Job Johnny. The hole can be wide open and the smell goes up the vent pipe. The toilet hole where it connects to your tank, needs an extension of two or three inches. Your vent pipe should connect with an inch or less intrusion into your tank. Also, a bathroom vent fan can help in those situations where the vent gets into a down draft.

[belfert]

If all else fails, this should solve your problem.   

We actually half seriously discussed renting a porta potty as a group while camped at an event.  We generally use the event supplied porta potties during the day to cut down on filling the waste tank.  Sometimes the potties are a decent walk away.  The rental company usually doesn't have any more space for another potty so that ended that idea.