Size of holding tank

[wingssail]

I think that 22 gal is a bit on the low side if it is actually being used and a trip to the pump out every few days is a pain. Some marinas offer pump outs at your slip, either with a cart on the dock or a barge which visits alongside. We've never been in a marina which has those services so we visit the shoreside facilities to avoid filling our 18 gallon tank.

To increase the size of our holding tank we raised the toilet 10 inches and put the holding tank underneath it, with a wood platform over the tank on which the toilet is bolted. The platform is 24x26 inches. This permitted a tank which extends into the bilge area. We don't have much bilge below the cabin sole but boats with deeper bilges could put a fairly big tank down there.

One bonus from our point of view is that the toilet is 10 inches higher than it was, a real "throne".

[Rumrace]

Hey Dr. In SeaRay language a “Weekender” had standard a thedford Porta Potti. So did the C&C built down the street from me. A Thedford “large tank” was 5 gal. I had that exact set up in a brand new 89 SeaRay Sundancer too cheap to upgrade the toilet. Daughter Son who always brought a friend. Ripped that toilet out and put in a pumping toilet and a 15Gallon holding tank which was tight fit in a 27’ boat.
My Jeanneau has an optional water tank and it comes in necessary on long trips.
In 2019 Lake Ontario Flooded. Our holding tank turns out to be 28G but you couldn’t get near most flooded clubs and half the pump outs on the lake were submerged. So wishing we had a larger sewage tank was a brief wish. Nothing worse then the vent squirting. It’s illegal to dump sewage in Canada. It was unethical before we had to make it a law for stupid people. Initially you could be fined for having the macerator system on board but never enforced.
Commercial boats do massive damage to the lakes and it was more to set them straight.
I read a good argument about sewage treatment in RVs and Boats. It’s a bio hazard you are controlling so it seems clever to never be without chemicals and plan the next pump out.
I was a member of a club almost the furthest dock from the club. No big deal I tend to leave before half the lawn chairs are deployed. The pump out system there beside the club blew up its septic tanks.
My slip was up wind behind a clump of trees didn’t smell a thing.
My Jeanneau sails better with full water tanks or it’s completely my imagination. Even fresh the holding tank has 1 gallon of water and chemical waiting. I learned that 50 years ago with Thedfords

[ranger58sb]

Originally Posted by Dr. D

My boat has a 22 gallon holding tank. When I found that out I thought that was on the small side.

If the inlet and vent fittings are on the side of the tank, you may not be using the whole 22 gallons of nominal capacity, either.

In that case, and if you have a bit of overhead space, you may be able to increase usable capacity by moving the inlet and vent fittings to the top of the tank.

-Chris

[shimari]

When we were looking for a new boat, it was difficult to find out the size of the holding tanks on most new and used boats. Brokers and shipyards often don't include that information. It's almost as if they know the tanks are too small.

There were several boats over 40' we looked at that only had a single ~40 liter tank. That's not going to last long with an electric toilet (my wife's only non-negotiable requirement). The HR 40C which we almost bought has an 85 liter (~22 gal) tank which is a bit more manageable.

We now have two tanks (80 liter and 60 liter). I plan to put a purasan on one of them so we have a hold, treat and dump when we're not in a NDZ.

[Dr. D]

As I was interested in what others have in their boats, I appreciate all the input.

Chris: All the fittings are on top of the holding tank, so I can use the entire tank. The marina I'm at has two pump out stations conveniently located, to stop there regularly even when the tank is only 1/4 full.

I agree with shimari that info on the holding tank is frequently missing from both new and used boat listings. Yeah, not a topic brokers or owners seem to want to talk about.

[boatpoker]

Originally Posted by Rumrace

It’s illegal to dump sewage in Canada. It was unethical before we had to make it a law for stupid people. Initially you could be fined for having the macerator system on board but never enforced.

Macerators (or any other sewage discharge method) were never illegal in Canadian Great Lakes, just that they were not connected. The Environmental Act, Ontario Regulation 343 states “ Water outlets for the head and/or holding tank must have no physical connection to an overboard discharge valve".

Neither The Canada Shipping Act, TP1332 or the Great Lakes Joint (US/Can) Commission make mention of the topic.

US Code of Federal Regulations Title 33 also permits such valves but requires ...

"Closing the seacock and removing the handle;
(2) Padlocking the seacock in the closed position;
(3) Using a non-releasable wire-tie to hold the seacock in the closed position; or
(4) Locking the door to the space enclosing the toilets with a padlock or door handle key lock."

[thomm225]

My holding tank is 6 gallons. It's an old Thetford plumbed in porta potti but I have closed the seacock. (and cut and caped the old hose to the pump out)

It will usually last me one to two months depending and I use my boat quite a bit.

I do though have to disconnect and remove it to empty.

The facility is across the creek.

If you only used proper toilet paper emptying is easy. It pours out just like thick beef gravy except with a slightly different smell........

The COVID Masks came in handy for this.

If far enough offshore, I use a bucket.

[BAD ORCA]

So after reading this thread, is it safe to assume his 22 gal tank is bare minimum for a couple that may want to go on 3-5 day'ish trips with no access to pump out and the inability to discharge overboard, assuming no guests?

[Rumrace]

That’s right Dr. Crew size trip plan. Someone told me 7 gallons a week per person. Have no idea if that’s fact more boat yard humour. I hope the boat makers did the math but as we read some boats have compromises, if not all. The optional 130l water tank is standard if it was a two head boat. The accumulator the manufacture chose seems great. The water pump is delayed and never runs on.
Just my wife and I most times so 40 gallon sewage tanks are not on our list. With two toilets they use a 15g saddle tank and it’s going to cost you two pump out bills to deal with tanks at different ends of the boat. When it comes to production boats I’d say what I’ve read the optional “extra” tankage should be standard for a cruiser and the base package a Weekender

[rslifkin]

How long a given size tank lasts will definitely depend on the toilets in use and the people too. Porta potty style toilets will go longer per gallon than a macerating electric setup, for example.

[thomm225]

Originally Posted by BAD ORCA

So after reading this thread, is it safe to assume his 22 gal tank is bare minimum for a couple that may want to go on 3-5 day'ish trips with no access to pump out and the inability to discharge overboard, assuming no guests?

No way.

If so that is like maybe pre-colonoscopy useage!

I have emptied my 6 gallon tank twice this season and have sailed maybe 20-40 times with multiple 2-4 day overnight trips.

Holding used for most "solids."

[rslifkin]

Originally Posted by thomm225

No way.

If so that is like maybe pre-colonoscopy useage!

I have emptied my 6 gallon tank twice this season and have sailed maybe 20-40 times with multiple 2-4 day overnight trips.

Holding used for most "solids."

You have a porta-potty style, which puts a lot less volume into the tank per use than other styles of head. So that helps a lot. And I get the impression that you're not putting much liquid in there at all, so you're using it far less than most of us do.

[ranger58sb]

Originally Posted by Dr. D

Chris: All the fittings are on top of the holding tank, so I can use the entire tank. The marina I'm at has two pump out stations conveniently located, to stop there regularly even when the tank is only 1/4 full.

Well at least it sounds like yours is as efficient as you can get for a 22-gallon tank.

Originally Posted by BAD ORCA

So after reading this thread, is it safe to assume his 22 gal tank is bare minimum for a couple that may want to go on 3-5 day'ish trips with no access to pump out and the inability to discharge overboard, assuming no guests?

I've read "personal discharge" is usually approx 1 gal per person per day. (Might be worth checking that elsewhere.)

If true, though, 5 days and two persons would be about 10 gallons of effluent, slightly less than half of a 22 gallon tank. Space for another few days... and/or even an overnight guest or two. Probably just a matter of management.

And then there's that access to pump-out thing. We've usually been luck enough to encounter facilities en route while on longer trips. More management. Depends on area, I suppose...

-Chris

[Rumrace]

If your interested in Canadas actual laws on sewage some regulatory commissions have based their statements on here they are.

https://laws-lois.justice.gc.ca/eng/regulations/sor-2012-139/fulltext.html

So there are several criminal charges for parking your RV over a city drain and since 2012 updates and corrections are a plenty.
The Great Lakes Association has smart devises on all the lakes tracking levels ,micro plastics, oxygen density. 2 meter long autonomous boats where in the harbour chasing plastic.
All this crazy activity is going to change laws.
Grey water tank is the next hurdle. The conversation will no die on the topic. It’s a massive problem in Toronto sewage system as drains and sewers have broken into each other.
It’s a very current topic in Quebec Ontario and British Columbia law societies pending changes in laws to interpret.

[thomm225]

Originally Posted by rslifkin

You have a porta-potty style, which puts a lot less volume into the tank per use than other styles of head. So that helps a lot. And I get the impression that you're not putting much liquid in there at all, so you're using it far less than most of us do.

Yeah that's true.

Liquid goes in large style plastic jugs which makes it easier also for aging males......