View Full Version : Stinky holding tank

09-03-2014, 06:35 AM
My HB is a pontoon style boat with a 70 gallon black water tank located under the flooring and midship on the 66' vessel. I have 2 toilets plumbed with 1.25" wastetank hose going to the holding tank with probably 5' - 7' runs each. The pump out line is hard plumbed with a thick PVC pipe exiting the tank and going to the stern of the boat. There's also a vent tube that's probably 1/2" that exits the tank and goes inside the boat's port wall and vents 1/2 way up the side of the port.

I have tried 3 different waste treatment chemicals on this boat, but none of them have really worked well. My neighbors at the dock are starting to regularily tell me that my boat stinks. The problem is at its worst whenever someone flushes a toilet. It'll clear the dock!

After talking to the boat's manufacturer, I know it doesn't have a filter in the vent tube, but I'm not certain I could even install one now if I wanted to because I don't have access to the tube. If I install one, it needs to be well above the waste tank so it doesn't get saturated when the holding tank is overfilled. How effective are these filters?

What can I do to improve this situation?

09-03-2014, 12:07 PM
Get more air into the tank. I have a fiberglass hulled boat with a 50 gal black water tank. I have a vent lines running to thru-hulls on both sides of the boat to give it cross ventilation with virtually no rise. My tank never smells. If you get enough air into the tank you get aerobic bacterial action as opposed to anaerobic which is what causes the horrible smell. According to Peggy Hall (who used to monitor this site and wrote a book on this subject) the more air the better and you should never have more than a 3 ft rise to your vents.

09-03-2014, 01:02 PM
I would agree that the problem is with venting. I don't understand why houseboat manufacturers take a vent that can bring vapors from the stinkiest thing on our boats and dump it at nose level. I had similar problems until I raised my vent so it now exits about 10 feet above my roof. I ran an extension in 1.5" ABS that exits my roof, turns to reach the side of my party top leg, then turns upward again to exit a few feet above the party top. Most of the things that make sewer stink are lighter than air so will drift up if you can just get them above nose height.

Depending on the age of the 1.25" hose between your heads and your black water tank, you might have another minor issue. After time, hose will age enough to allow vapors to permeate where liquids won't. You can test that by wiping the hose with a damp cloth then smelling the cloth. But this is a minor issue compared to where your vent is dumping smelly gasses.

09-04-2014, 05:10 AM
I understand Peggy Halls point, but most houseboats were not built with 1.5 in cross flow vent lines and air bubblers in the waste tank. So, here is what I would (and have done):

1. Do not let your waste tank overflow - it is simple to keep that from happening.
2. Replace as much of the flex drain hose as possible with 1 1/2 in hard PVC
3. Install a Big Orange filter - http://bigorangefilter.com/ - in your vent line. As long as it is not kinked, you can run the 1/2 vent line wherever you want. I would replumb it in 1/2 in hard PVC and install the Big Orange filter where you can easily get to it to replace the activated charcoal that is the filter media.
4. Pump your tank, fill it with water, pump again, and repeat a couple of times. Then start using Odorlos as your treatment - it will provide oxygen to your tank to try to grow aerobic bacteria.

This will work. Even in the 97 degree heat down here in GA, my tank vent does not smell.

09-07-2014, 03:36 PM
Or rip all that nasty stuff out, heavy holding tanks, stink-saturated hoses, etc, etc, and install simple, smell-free composting heads.:D ;) And never pump out again. :cool:

09-11-2014, 05:32 AM
Several of my dock neighbors installed a waste step treatment tank. It has 3 chambers that progressively breaks down waste and finally dumps it to the water. Our lake is still a 'no dumping' lake, but TWRA and CG don't enforce it at all. I'm one of the few boats at my marina that pumps out.

I've actually stopped tying up with several of those other boats b/c I cringe to think that my kids and I are swimming in their toilet waste water.

09-12-2014, 06:43 AM
The TWRA is not going to enforce anything except people acting stupid on the 4th of July - they won't even walk the docks and hand out tickets for expired stickers. Your marina owners should be enforcing it. They will be the ones with the big fine from the Corps and the CG.

09-12-2014, 10:39 AM
I know that the marina owner and his top staffer both have their boats dump into the lake. I've never seen either one of their boats leave the slip. He recently invested in a mobile pump-out boat, but every time I call the office, it's not running. They finally admitted they pulled the outboard off of it to put to service on one of the rental boats, so they wouldn't lose any income.

09-15-2014, 05:35 AM
There is not much you can do if the marina owners do no care. Eventually the Corps will come around and start checking. TVA did it on all their lakes about 8 yrs ago. Basically put the marina owners on notice that they would revoke their leases if they did not keep on top of it.

Sooner Fan in Branson
08-17-2015, 02:34 PM
I copied and pasted from another section, but this is what I wrote.

I've never posted before, but after the issues I had when I bought my boat from a gentleman who apparently wasn't concerned about the smell from the top of the boat or the dock neighbors around him, I had to reply. First thing was my awesome neighbor Dave suggesting that I start using Kronen septic treatment and not to flush anything that can kill working bacteria, and after a little while the smell got somewhat better. Last thing was after hours of research I decided to buy a unit from OdorHog which was extremely easy to mount on top of my boat. It doesn't look bad and completely got rid of our odor problem. I know that I will have to eventually replace the charcoal in it, but I don't about puke every time someone flushes the toilet.

09-02-2015, 10:31 AM
I ended up taking the wall panneling off the wall to expose the holding tank vent hose. It was 3/4" ID white spa hose and it was indeed permiated. I removed it and replaced it with a high-density PVC pipe and a homemade carbon filter canister that I put together at Home Depot. Once install and everything put back in-place, everything worked as planned! I've been odor-free for over a week now and my neighbors and I are getting along better already. Thanks for the advice guys!

12-28-2015, 04:27 PM
You can make a facsimile of an OdorHog for about $12 spent between Lowes and Walmart. PM me and I'll send pics and instructions