Size of holding tank

[Dr. D]

My boat has a 22 gallon holding tank. When I found that out I thought that was on the small side. The diesel tank and fresh water tanks are each 34 gallon.

From what I now understand, my diesel tank is fine, but my water tank">fresh water tank is very limited.

OTOH, it seems many “cruising” boats have even smaller holding tanks. Is that because the designers figure their boats will be upon the open seas and discharging direct into the sea?

[S/V Illusion]

Not sure what you describe as a “cruising” boat but regardless, near shore sailing boats have proximity to pump out facilities and offshore boats don’t need pump out facilities. So neither really needs a large holding tank.

[silvercreek]

22 gallons seems big to me... Mine has two 8 gallon tanks for 16 total.

But it has a big ole 45 gallon fuel tank and 80 gallon water tank.

[5BTM]

My CS27 has a 32 gallon holding tank, 15 gallon water tank and 16 gallon fuel tank.

First offseason project is throw out the entire toilet/tank assembly, remove and glassing in the through hulls, Replace with OGO.
My wife and I hate having all that crap sloshing about under the v berth.

Second one is to ditch the water tank and the stupid pressure water system.
Without the holding tank I will easily have room for eight 5 gallon water bottles.

Keeping the fuel tank for now.

[ItDepends]

The size of fuel, water, and holding tanks all depend... How do you use your boat???? You have not given us a clue, so any answer is as likely to be wrong as it is to be right. There is no one answer for everybody, and shouldn't be. I am not at all sure why you thing the size of your holding tank has anything to do with the size of your fuel tank... or your water tank...

The idea of an "offshore cruising boat" is silly. No boat spends most of its time offshore.

In my experience (and I have a lot of it...) a 35 gallon holding tank lasts two people about a week, in full time liveaboard use then it needs pumping out. That is a fuzzy number, since it depends on the toilet, the habits of the people, and the availability of shoreside facilities.

Another consideration, are you comfortable "camping" on your boat? or do you prefer a more civilized lifestyle?

If you are a weekend cruiser (as most people here are), 22 gallons is just fine.

[Dr. D]

Hey, I am trying to investigate what is a reasonable size holding tank. Not meaning to create a standard. Geez, relax…..

[Cyrus Safdari]

Might want to consider getting an MSD and be done with the holding tank hassle though it is a bit pricey
Uses less space and the effluent is cleaner than seawater

You'll only need a holding tank if you're in a no discharge zone in which case you can plumb in a temporary flexible bladder or use a camping potty

[NYSail]

My last boat Pearson 36-2 had 12 holding, 22 fuel and 75 water….. for what we do it wasn’t enough. Boat was not built with a holding tank….. a later addition as is the case with most older boats I assume. New boat has 2 25 holding, 52 fuel and 150 water…… makes cruising so much easier for us……. Each persons needs are unique.

Greg

[grantmc]

Originally Posted by 5BTM

My CS27 has a 32 gallon holding tank ---
My wife and I hate having all that crap sloshing about under the v berth ...

Totally agree with the sentiment. 32 gallons (120 litres approx.) of slimy sloshing sewage isn't likely to set the atmosphere for a sexy time on the v-berth.

[goboatingnow]

My 2004 Bav 36 has 300 litres water 150 litres diesel and just under 90 litres holding. The holding tank is very convienently located in side of the s/board locker all bits accessible.

Thankfully my arm gets fully through the inspection hatch and at it’s full extent I can reach the tank bottom ,good thing the contents of the blocked tank Monday last was easy to reach by my hand and extract a few handfuls of stuff out to free the 90 litres of effluent. !!

Seemingly my arm is fine. ……..

[Mike OReilly]

Previous boat had a 35 gallon holding tank. This was a Great Lakes boat, so zero-discharge allowed. It was never enough for the two of us while travelling the northern Great Lakes where pump out facilities are few, and very far between.

Current boat came with a 25 gallon tank. Way too small. It's part of the reason I switched to a composter.

Now that I'm based in semi-remote Newfoundland, few boats have any sort of holding capacity, even though most boats rarely venture out beyond the 3-mile limit. I still prefer our composter.

BTW, we also have a 60 gallon diesel tank and a 200 gallon water tank, although I'm not sure how that relates to size of holding tank.

[goboatingnow]

Since I switched to an electric toilet it consumes more holding tank, now 2-3 days whereas before 4-5

[rslifkin]

Our 38 footer (power) has a 70 gallon holding tank. I'd say it's pretty well sized. With the 2 of us on board, we can comfortably go 10 days before needing to get the tank pumped out.



Many of the sailors locally with small holding tanks (15 - 25 gallons) complain about them regularly. They try their best to avoid using the head onboard when in a marina, and if they have guests out for a sail, it's not uncommon to need to pump the tank after a single day.



Just like with fuel or water, being able to go longer before you need to stop in for anything is a big convenience. In many areas, an extra couple of days of holding tank capacity means you'll hit an opportunity to pump the tank before it's full rather than having to go looking for one because the tank is almost full.

[Shrew]

The size of the holding tank seems to be dictated by a few variables:

1) Type of head; I notice that electric flush models tend to have larger holding tanks than vacuflush, for example. Mosts likely a result of the amount of water each uses to flush.

2) Number of heads; This one is weird, because IMHO, it should really be number of staterooms, since that is more indicative of the number of passengers.

[leecea]

The few holding tank installations I've seen have been tight fits and I'm not sure how you'd put in more tank space. IMO 22 gals isn't bad and maybe you just have to figure out how long you can go between pump outs and factor that into your plans.

We have 30 gals but pump out before its full anyway, so probably not using more than 22 gals.