Holding tank Alternative

Holding Tank Pitfalls

I’ve been perplexed by our holding tank for some time.  We estimate it holds a whopping 15 gallons.  We only use it now for #1 and only in the morning and maybe once at night.  Luckily the marina bathrooms are uber nice and we’re both gone at work all day during the week so it usually isn’t an issue.  However, it seems ridiculous that it’s so small and we do have to pump out every two weeks at $15 a pop.  I’ve asked around to other boat owners in our marina and ours is by far the smallest.  Then Rich looked on the Tayana Owner’s Group website and ours seems maybe on par for the age of our boat (1977); the newer ones have a larger tank.  I guess back in the ’70s everyone just pumped overboard.  One Tayana owner commented that he added a septic treatment to his tank and after letting it sit for a few days to dissolve all the solids (ick) he was able to gain several gallons (I think he said he went from about 15 to 25).  I don’t believe that would happen with ours because our dip tube is already an inch or two above the bottom of the tank.  If there is a solid layer down there that we could get out to gain more space, the dip tube wouldn’t be long enough to be effective.  About two years ago, before we move aboard full-time, we thought about adding another holding tank, but there just isn’t enough room.


After some long discussions about how we plan to use this boat, we decided to install a type I marine sanitation device (MSD).  While in the Delta for the next few years we plan to anchor out for the weekends and take some longer trips to the Bay Area, Monterey, Drake’s Bay, etc.  We realized would fill the holding tank up in a couple of days.  Plus, when we do finally head farther south and west, it’ll come in handy if we’re anchored in a nice lagoon and don’t want to leave to empty the holding tank.


Pumping out isn’t that big of a deal, but this is the Delta and those types of services can be unreliable.  After a lot of research we decided to buy a Raritan Electroscan.  We’re going to put it under the port settee just aft of the head bulkhead.  Unfortunately, since we are in fresh to brackish water now we also have to install a salt feed tank.  Luckily, we have room for it on the shelf behind the port settee just above the Electroscan unit.  All of it will be hidden from view and when we head offshore we can ditch the salt feed tank since we’ll be in saltwater and gain that storage area back.  We thought about going with the Purasan, also made by Raritan, but instead of salt you have to use their special tablets which are expensive and might be hard to get in other countries.

Rich will write a post with all the gnarly details about how hard it was to install and how this one project created 15 others…and so it goes.

Fall Projects
Two tears in a bucket


  1. I am happy you didn’t have to dissolve solids.

  2. I’m really interested in the gnarly details you might have on the Electroscan install. I’ve been considering this unit for a long time. My understanding is that it’s not legal to pump the output of the Electroscan over the side either so don’t understand the benefit of the purchase. If I could pull out the holding tank and use the space for the Electroscan I would do it in a heart beat. Isn’t the poop purified so it has no impact on the environment ?

    1. Hi Rich – Actually it is legal to pump out of the Electroscan over the side in all areas except the EPA’s designated No Discharge Zones (NDZ). The only NDZ in our area is Richardson Bay which is way over by Sausalito. You can read about the NDZ at this link http://www.epa.gov/sites/production/files/2015-10/documents/california_ndz_final_rule_factsheet.pdf. Boat US also has some good info about how the Type I MSDs work at this link http://www.boatus.com/boattech/articles/msd.asp. The effluent must have a fecal coliform bacteria count not greater than 1,000 per 100 milliliters and no visible floating solids. The USCG has an approval process for Type I MSDs and I believe Raritan has received such an approval for their devices.

      Rich spent all day just trying to figure out how he is going to run the wire for the unit and I’m not sure he has it figured out just yet. I’m hoping that rewiring the entire boat and installing the new electrical panel didn’t just get bumped up to the top of the projects list.

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