Waste line route to holding tank - which would be best?

I am replacing waste lines and need advice. Toilets are Jabsco 37010 electric flush. Most would say to replace both with Raritan Elegance, but with so many other updates going on that is not in the budget.


Short version of my question: Am I better off with either option A (2 climbs in elevation) or option B (only 1 climb in elevation, but about 10 feet away from the pump)?
Route Option A: run waste hose up about 20" about a foot after it leaves the toilet/pump/motor to very quickly reach highest elevation into either a Y-valve (if I keep the direct discharge option) or a vented loop, and then hose would drop down about 2 feet in elevation to get under the companionway flooring, then go about a 10 foot level run to get through a bulkhead. Then (and here is the trouble), it needs to climb about 18" back up in elevation to get to the holding tank inlet. So, that is one climb in elevation near the pump up about 20", then after dropping down lower, another climb of about 18" to get to the holding tank (2 "rises" is what bothers me) OR
Route Option B: Not climb in elevation anywhere near the pump. Just run it from the toilet, then down under the companionway for the 10 feet level run, then make the only climb in elevation take place after the bulkhead near the holding tank. The rise in elevation could then be about 2 feet or 18", into a vented loop or Y valve (if I choose to keep the direct discharge as an option), then into the tank. I like having only one rise in elevation. What bothers me about option B is while there is only 1 rise in elevation, it takes place about 10 from the motor on the electric toilet. Not sure if this is good or trouble/clogging waiting to happen.

More details in next post if you care to know more. I was trying to keep this as short as possible. Thanks for any thoughts.

More details:
Toilet is about 16" above the water line of the vessel if this matters.
There is currently a Y-valve to go to the holding tank or direct discharge. I was considering cutting out the Y-valve making it go to the holding tank only. Holding tank has deck pumpout option or overboard discharge (to be used, of course, only where appropriate/legal/acceptable/etc.) so we can still discharge where appropriate but from tank instead of directly from head.

In either option A or B, my intention is to use very good waste hose, and still replace with PVC in all sections where possible.

In option A above, the first rise in elevation to the vented loop (or Y-valve, or both) is the highest rise in elevation. The second rise about 10 feet later is not quite as high, but still two rises seems troublesome.
Toilets are both raw water flushing and that will be the case for now (again, not in budget to change this right now).
Why is vented loop necessary on waste line? is it to make sure it never siphons back from holding tank if tank is mostly full?

You want to avoid "uphill" as much as possible. We do have a true industry guru who frequents this site, so hopefully she will chime in. But the described routing has me puzzled. Are there boats really designed that way?

Listen to Peggie. . She should chime in.
My opinion is option B is essentially creating a very large trap and will be a problem unless you figure out how.mych you need to flush to clear the whole line and that will likely fill the tank fairly quickly.
Can you go more directly (level or higher close to the tiolet) to the holding tank and add a macerator pump from tank for overboard discharge?

I think the location of the rise is less important than how high the highest rise is.
The ideal set up is down hill all the way from toilet to tank. Any rise above the toilet means that you’re relying on the joker valve to prevent back flow to the bowl. The higher the rise the more back pressure on the valve.

HopCar said:

I think the location of the rise is less important than how high the highest rise is.
The ideal set up is down hill all the way from toilet to tank. Any rise above the toilet means that you’re relying on the joker valve to prevent back flow to the bowl. The higher the rise the more back pressure on the valve.

Click to expand...

True but I'd rather have 1 Qt of water against the joker rather than 1 Gal as it's easier to make sure the 1 Qt is clean " flush" vs waste.

Bacchus said:

True but I'd rather have 1 Qt of water against the joker rather than 1 Gal as it's easier to make sure the 1 Qt is clean " flush" vs waste.

Click to expand...

Good point

caltexflanc said:

You want to avoid "uphill" as much as possible. We do have a true industry guru who frequents this site, so hopefully she will chime in. But the described routing has me puzzled. Are there boats really designed that way?

Click to expand...

Thanks for your thoughts. I will add a post below and try to attach a picture that might help. The guest head is on the port side of the boat. Holding tank is to starboard. Waste route goes under companionway sole between galley and dinette areas, then to the holding tank after passing through a bulkhead to get to the engine room area.

As far as avoiding uphill, the top of the holding tank is for sure lower than the vented loop, or a Y-valve. The top of the tank and the top of the toilet are about the same height, but of course the vented loop or Y-valve are higher. The pump has no trouble lifting a couple of feet, and that is all it takes. But I don't like the idea of lifting, then dropping down and lifting again. Even though the 2nd lift is considerably lower than the top of the loop -- so it should effectively drain since it was already lifted higher -- I just hate that 2nd climb.

The only way to avoid that is to wait 10 feet before making the lift, as in Option B. Waiting to lift once, only when it gets near the tank, puts the lift 10 feet away from the pump on the back of the toilet that I wonder if that will cause more problems. I might be better off lifting early, even though it needs to go downhill then back up. BTW, it was originally installed with option A. I just wonder if Option B would be an improvement, or a drawback.

I was hoping Peggie Hall would chime in on this. You might send her a PM. Theheadmistress.

Bacchus said:

Listen to Peggie. . She should chime in.
My opinion is option B is essentially creating a very large trap and will be a problem unless you figure out how.mych you need to flush to clear the whole line and that will likely fill the tank fairly quickly.
Can you go more directly (level or higher close to the tiolet) to the holding tank and add a macerator pump from tank for overboard discharge?

Click to expand...

I think you have an excellent point about option B essentially creating a very large trap, and the amount of flushing to clear it. That makes a great argument for lifting high early, then lifting a little after it gets to the tank (which is option A, and how it was originally set up).

And there is a macerator pump from the holding tank for overboard discharge (when/where appropriate, of course).

Since there is a macerator pump, I was considering abandoning the Y-valve and just having a high loop, so it has to go to the tank. Although I did see once where Peggy suggested having your vented loop, then your Y-valve (essentially stacking them) and then your vented loop is serving both lines (direct overboard and to holding tank). I do like that idea.

Thanks for your thoughts.

Maybe a picture will help. Thanks for the advice on this, everyone. Hopefully it attached and can open.

After reading all this, IMO the routing of your toilet-tank line needs some major redesign. WHY does it have to drop down about 2 feet from the vented loop to get under the companionway flooring, then go about a 10 foot level run to get through a bulkhead. ...and THEN climb about 18" back up in elevation to get to the holding tank inlet??? Surely there's a lot simpler, more straightforward route and I'll be glad to help you find it.


--Peggie

You posted your schematic while I was typing...is there any chance we could relocate the tank?


--Peggie

Yes, looking at your drawing neither looks to be a good choice to me. Your lines will have sewage in them all the time unless you pump gallons of water after each use. Better be a big tank...

HeadMistress said:

You posted your schematic while I was typing...is there any chance we could relocate the tank?


--Peggie

Click to expand...

Relocating the tank would be quite a project, but possible. A better solution would be to reroute the line from the port side forward head, around the outside of the port side dinette (which is just aft of the head and just forward of the bulkhead). The line could cross from port to starboard without dropping down under that companionway sole because it would already be in the engine room (so no need to go low). I think that is the ultimate solution if this causes problems.

It is not an easy reroute, but will do if need be. I will have to tear into some cabinets, and move a few things on that bulkhead.

It has run like this for 30 years and it must have worked as the previous owners did use the boat extensively.

I am hoping that since the top of vent/loop can be considerably higher (around a foot) than the top of the holding tank, that things will flow pretty well despite the "uphill" near the tank. I am actually raising the height of that loop compared to how it was, which I think will only help matters unless I am misunderstanding something. I am also using PVC for most of the run. Finally, I am using high quality hose where hose is required. Hopefully all of these things will decrease the odds of trouble.

Obviously the pump/motor on the toilet is a macerator so the solids should be minor. If it was 100% liquid, I would not be concerned. I guess I will know soon how problematic it is. I really appreciate the thoughts. Thanks everyone.

I have a similar design issue with my aft head where it's fairly far away from the holding tank and not a lot higher than it. IMO, if you have to go up a bit, do it as close to the toilet as possible to make it easier to keep the non-draining part of the line full of clean water. And then all downhill from there.

For the Y-valve, if you have the ability to dump the tank overboard, I'd ditch the Y-valve for simplicity. Less connections, less hose and in theory it should let you eliminate a thru hull.

Neither of the routes in your drawing would be a good choice...the wavy one with dips in it would be a horrible idea, just asking for a clog.



Relocating the tank would be quite a project, but possible.

And worth doing because 6' is about as far as the typical manual or electric toilet can move bowl contents with a reasonable amount of flush water without a LOT of help from gravity. It's not necessary for the loop--which doesn't have to be vented if you're only flushing into a tank--to be a mile high--your toilet can lift up to 4', but that's about all. .. just a few inches higher than the top of the tank, then down all the way to the tank inlet fitting. And also immediately after the toilet (elbow discharge fitting aimed straight up), so that you only have to flush long enough to push the flush over the top of it...gravity will do the rest. That the waste will be macerated only means that the salt and sea water mineral buildup will be mixed with waste particles.


How big is the tank? 'Cuz if "it has run like this for 30 years and it must have worked," that may be true only because the previous owners filled the tank with more flush water than waste trying to keep the toilet discharge hose rinsed out enough to prevent clogs...and you have no way of knowing how successful they actually were in doing that.So it's entirely possible that a smaller tank in a location that makes sense (a LOT closer to the toilet!) would hold even more actual flushes...not to mention make plumbing it a lot simpler requiring a LOT less pipe. Ronco Plastics makes top quality water and waste tanks for a very reasonable price and have more than 400 shapes and sizes, over 100 of which are non-rectangular, and they install fittings in the sizes and locations specified by the customer when they make the tank. Ronco Plastics marine Tanks


And btw, although hard PVC is less expensive and odor permeation-proof, it's still just as susceptible to sea water mineral buildup as hose, and also requires a bunch of unions that not only complicate installation, but also trap bits of waste with the minerals. I'd go with Raritan SaniFlex hose Raritan Saniflex Sanitation Hose (Defender has it for about $10/ft), which has also proven to be 100% odor permeation resistant and has the added advantage of being so flexible it can be bent like a hairpin without kinking...which makes re-piping a LOT easier!


--Peggie

Boy, it's a shame nobody here knows what they are talking about.
Just kidding, Peggie. I very much appreciate the detailed and dead on analysis/advice. You clearly know your stuff! Thanks for taking the time to share your thoughts.

I have been getting advice from Peggie for almost 20 years. And it has always been dead on. We are very lucky that she is on TF.

One more thought to share with you: When it comes to sanitation systems, the simpler it is, the fewer the problems with it.



--Peggie

"stuff " flows downhill...always has,always will. I can't imagine trying to boost stuff uphill on a boat..I think a redesign is in order

Sailor of Fortune said:

"stuff " flows downhill...always has,always will. I can't imagine trying to boost stuff uphill on a boat..I think a redesign is in order

Click to expand...

I agree. With the lenght and uphill it will constantly take a lot of water pumped after each flush to keep the long hoses clean. Better a closer downhill tank even if it is smaller you would probably get more uses before having to pump out.

Any longish run ,I would have PVC pipe instead of hose and hose at the connections where needed

My forward head has a long run to the holding tank. Most of it is PVC. Unfortunately there are several 90s in the run. However it has not caused me any problems yet.

Even though PVC does have some disadvantages that Peggy pointed out, for a long run without a lot of drop, I'd still use it. It'll be easier to maintain a steady down-slope without any dips using rigid PVC instead of hose for the long part of the run. And that means less standing effluent in the lines, etc.

Vacuflush

For you Headmistress, I need to replace the pump bellows in my Vacuflush. I have all the duckbills and the bellows and o rings. I am vacillating between doing it myself, (then I'll know how to fix it again if need be) or having the yard genius at the marina do it. I'm a pretty fearless DIYer, but I'm a bit intimidated by this project. Any advice?

Also, apologies for hijacking the thread, but gosh for the original poster, it all sounds soooo complex. Anything on a boat should follow KISS. My dad was a HVAC guy and tried all kinds of simple solutions to things when they got too complex. They usually worked too!

If you can read then actually FOLLOW directions, it's an easy job. If you'd like for me to walk you through it one-on-one, send me a PM that includes your email address (unless you already have mine, in which case send me an email) and I'll be happy to help you.


--Peggie