Marine Toilets

Discussion in 'Boat Design' started by Mik the stick, Oct 15, 2015.

  1. Mik the stick
    Joined: Dec 2012
    Posts: 189
    Likes: 0, Points: 0, Legacy Rep: 6
    Location: Devon

    Mik the stick Senior Member

    Just read an article on curing the bad smell marine toilets produce. the cure was to put the toilet in the wheelhouse where it was well ventilated. He also expressed a preference for a curtain rather than a door. Privacy on long cruises may be difficult to achieve but not highly prized by the auther of this article. Not my idea of a cure at all. The salt in the sea water flush system promotes smelly bacteria. So here is my suggested cure.
    A Nordhaven 46 has a 350Usg fresh water tank a toilet flush us about 2usg per flush. If a person drinks 1usg per day uses 6 more to shower, and uses the toilet twice That totals 44Usg per day with 4 people aboard. That means water will last 8 days So a water maker is a must have.
    1. Increase the freshwater tank size if possible and use freshwater to flush the toilet.
    2. Install an extractor fan in the toilet and run it permenently. Vetus make a 12 volt one which draws 150Ma and extracts 70 cu meters of air an hour. which should change the air every 5 minutes or so. You could rig up a timer and run the fan fo 5 minutes every half hour or whatever was required.
  2. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    I guess you're not talking about under the waterline toilets here: it would be a waste to flush these with freshwater.

    Toilets with a holding tank should have a blade like the ones in camper vans. If seawater promotes smelly bacteria in the tank, use an extractor van in the tank vent to maintain a slight vacuum.
  3. philSweet
    Joined: May 2008
    Posts: 2,599
    Likes: 374, Points: 83, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    The problem is usually little marine critters dying and creating a stink in the bowl. It's an estuary, marina, and mooring field problem. Normally not a problem at sea. Use fresh water rinse in the marina. Use salt when cruising. It takes about a cup of fresh to rinse and purge the bowl. Most people use the shower head hose. Use a bit more fresh if everyone is going ashore for the day. I only have a 35 gal fresh tank plus two jugs, and a 14 gallon holding tank, so limit of about 1 gal fresh per person per day cruising. As far as flushing goes, I use the "If it's yellow, let it mellow, if its brown, flush it down" system.
  4. Yobarnacle
    Joined: Nov 2011
    Posts: 1,747
    Likes: 130, Points: 63, Legacy Rep: 851
    Location: Mexico, Florida

    Yobarnacle Senior Member holding true course

    Urine isn't sewage. Not matter in suspension. Has no particles of ANY size. Contains NO coli bacteria. Can go straight overboard.
    All requirements of treated sewage specify max particle size and max amount of coli bacteria permitted..
    Urine simply needs no treatment.
    Feces host two basic types of bacteria, Aerobic and anaerobic. The first needs oxygen, the second thrives in airless environment. Anaerobic bacteria cause stinky gasses. Aerobic bacteria doesn't cause stink.
    A compost head uses fibrous material incorporated with the feces to provide air to the mass. Insures non-stinking aerobic bacteria enviroment, and inhibits the anaerobic stinky bacteria.

    In a liquid sewage holding tank, it's pretty difficult to avoid funky anaerobic bacteria.
    Ventilation helps though.
  5. cmckesson
    Joined: Jun 2008
    Posts: 161
    Likes: 7, Points: 18, Legacy Rep: 55
    Location: Vancouver BC

    cmckesson Naval Architect


    I have been considering installing a bubbler in my sewage tank, with the intent of promoting the aerobic bacteria. Any thoughts on whether this would reduce odors?

    The mechanics of it I have. It's just the biochemistry of it about which I am unsure.

  6. Yobarnacle
    Joined: Nov 2011
    Posts: 1,747
    Likes: 130, Points: 63, Legacy Rep: 851
    Location: Mexico, Florida

    Yobarnacle Senior Member holding true course

    aerobic bacteria needs air, and air kills anaerobic bacteria. Sounds like it might help.
    Avoid advice like putting vegetable oil in your toilet. It definitely seals the surface of the liquid and encourages only stinky anaerobic bacteria. Yet I hear folks give that bad advice to their friends.
  7. Squidly-Diddly
    Joined: Sep 2007
    Posts: 1,916
    Likes: 161, Points: 63, Legacy Rep: 304
    Location: SF bay

    Squidly-Diddly Senior Member

    Yeah, those anaerobes will knock your socks off.

    Wasn't there an all electric feces-fryer totally odorless crap-crematoria that turned everything into a non-infectious odorless grey powder? Maybe just an experimental version?

    What about that engine exhaust powered idea?

    There are fancy washer/dryer combo machines from Germany that very efficiently dry the clothes not with heating lots of air but by taking the humidity out of air. Could such a system be used to reduce human waste to virtually odorless solid with low power use?
  8. Yobarnacle
    Joined: Nov 2011
    Posts: 1,747
    Likes: 130, Points: 63, Legacy Rep: 851
    Location: Mexico, Florida

    Yobarnacle Senior Member holding true course

    It's called a compost toilet. :D
  9. NavalSArtichoke
    Joined: Oct 2013
    Posts: 431
    Likes: 9, Points: 0, Legacy Rep: 83
    Location: GulfCoast

    NavalSArtichoke Senior Member

    I think the US EPA and the environmental authorities of the several states would strongly disagree with your opinion that urine can be discharged without treatment, from a vessel or otherwise. Unless you're peeing Evian water out yer nozzle, urine needs treatment. You don't get a pass 'cuz there's no "captain's log" to worry about.
  10. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    It is always the same: all these rules come from institutes where neckties are in fashion. They pull them too tight, cut off bloodstream to the brain and start writing nonsense.

    Like Yobarnacle wrote, urine contains nothing that needs "treatment". With the possible exception of a few small kidney stones, urine is a sterile liquid containing various salts, dead bacteria and some compounds like urea and bilirubine that have been circulating in the bloodstream. In fact the kidneys are the best possible waste treatment facilities you can imagine.
    Some people even drink morning urine to improve their health.
  11. Yobarnacle
    Joined: Nov 2011
    Posts: 1,747
    Likes: 130, Points: 63, Legacy Rep: 851
    Location: Mexico, Florida

    Yobarnacle Senior Member holding true course

    The EPA regulates sewage, which urine is not.
    I'm not surprised a few states have draconian laws.
    Florida isn't one of them.
    In truth the EPA has no authority over commercial vessels under 79 feet, and none at all over private yachts. The Coast Guard does.
    "EPA's NPDES vessels program regulates incidental discharges from the normal operation of vessels consistent with section 402 of the Clean Water Act. These incidental discharges include, but are not limited to, ballast water, bilgewater, graywater (e.g., water from sinks, showers), and anti-foulant paints (and their leachate). Such discharges, if not adequately controlled, may result in negative environmental impacts via the addition of traditional pollutants or, in some cases, by contributing to the spread of aquatic invasive species.

    The centerpiece of the NPDES vessels program is the Vessel General Permit, also known as the VGP. The VGP was issued initially in 2008 with that permit in effect through December 19, 2013. EPA reissued the VGP on March 28, 2013 with that second permit taking effect beginning December 19, 2013 (and effective for five years thereafter). Generally, the VGP provides NPDES permit coverage for ballast water and for other discharges incidental to the normal operation of commercial vessels greater than 79 feet in length and operating as a means of transportation.

    Except for ballastwater, NPDES permits have not been required for discharges incidental to normal operation of commercial fishing vessels and other non-recreational vessels less than 79 feet. Because the moratorium from the requirement to obtain permit coverage for incidental discharges from these vessels was extended until December 18, 2017, see Vessels Background, beginning December 19, 2014, owners/operators of vessels less than 79 feet in length with ballast water discharges will be able to obtain NPDES coverage under EPA's Small Vessel General Permit (sVGP), which was published on September 10, 2014 (see Small Vessel General Permit).

    Recreational vessels are not subject to the requirement to obtain an NPDES permit for discharges incidental to their normal operation. Rather, the law requires EPA to develop management practice performance standards and then for the Coast Guard to promulgate regulations that require compliance with such practices. Similarly, the NPDES program does not regulate discharges from military vessels. Both recreational vessels and military vessels are regulated under the authority of Section 312 of the Clean Water Act."

  12. hoytedow
    Joined: Sep 2009
    Posts: 5,857
    Likes: 399, Points: 93, Legacy Rep: 2489
    Location: Control Group

    hoytedow Carbon Based Life Form

Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.