Is it OK to install blackwater tank above the toilet discharge outlet?

[EvilRabbit]

Getting raw water slowly dribble back into the bowl and having to flush 2-3 times to clear the lines. I assume this is what is in the line between the tank and the discharge outlet of the toilet. Is the issue here is that the holding tank has bee fitted above the discharge and pipe running 90 degrees for half the distance?

[Sailmonkey]

If you have waste flowing back into the bowl you need to replace the joker valve on the head. The installation, from the photos, looks ideal.

[peghall]

A brand new joker valve will block backflow, but every flush stretches the slit and "lips"...in a short time (how long depends on how much use the toilet gets you'd be able to see daylight through it, which is enough of a gap to begin to allow very slow seepage...gradually increasing. So you'd have to replace the joker valve as often as every couple of months to prevent backflow completely. But that would create another problem: waste left sitting in the discharge will lead to a stinky hose. In fact, judging from the color of it, I suspect it's already seriously permeated.

Relocating the tank is the only good solution. It has to be sitting on something...What's below it? If that won't work, is there any available lower space within 6-8' of the toilet? Or even further...it's better to have a longer discharge hose than what you have. How long is the discharge hose now?

And btw...What's the make/model of your toilet? Does it have a "dry bowl" flush option?

Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

[Pizzazz]

There are some boats (Halberg-Rassey's) that have the holding tank above the bowl level and then use gravity discharge, so it could be done as long as you are OK to replace the joker valve often.

[Quebramar]

On my Najad the tank is also above toilet level. When buying the boat 3 years ago I changed the joker valve and since, no issue whatsoever. I do pour a bit of salad oil on a regular basis to keep the joints and valves lubricated and it works wonders.

[Cheechako]

You need to flush more. Even if the joker is leaking then the water seeping back will be clear.

[Sailmonkey]

Originally Posted by Cheechako

You need to flush more. Even if the joker is leaking then the water seeping back will be clear.

There is this as well. Our tank is about 2 feet above the bowl. when flushing I pump the volume of the hose worth of clear water (simple calculation for pump strokes to hose volume) then pump dry vigorously to eject as much fluid from the line as possible.

[Kenomac]

You need to flush with enough water to clear the waste hose for two reasons. One to prevent waste from permeating odors through the hose, and two so that any fluid that trickles back will be clear.

[Quebramar]

Originally Posted by Kenomac

You need to flush with enough water to clear the waste hose for two reasons. One to prevent waste from permeating odors through the hose, and two so that any fluid that trickles back will be clear.

Do you have a given rule of thumb, say 10 ?strokes fresh water flush then as much as needed to empty the bowl?
I know a friend who asks for 20... sounds a lot to me though. Of course it's a matter of pipe size as well as what you stuff in...!

[Quebramar]

Sorry I meant sea water [emoji17]

[Kenomac]

We have an electric macerating head, so two full bowls will flush all the way out to the through hull fitting. You'll need to experiment with the pump.

[HopCar]

I think the original question has been answered, change the joker valve often or better yet lower the tank.

Gravity is your friend, lower the tank.

There was some confusion, mostly me, about what kind of water was flowing into the bowl. To me the term "Raw Water" indicates water brought into the boat from outside, usually seawater. Once the Raw Water passes through the toilet it becomes "Black Water". I think everybody figured out that the OP meant black water when he said raw water. Sometimes it takes me a little longer to figure this stuff out.

[Kenomac]

Our tank is above the toilet by almost three feet, no problems. No need to lower your tank.

[model 10]

Also the hose/fitting is supposed to drop or point down just a bit at the pump. This is per the PHII manual.

[StuM]

Originally Posted by Kenomac

You need to flush with enough water to clear the waste hose for two reasons. One to prevent waste from permeating odors through the hose, and two so that any fluid that trickles back will be clear.

Agree 100% with the previous posters who have said this.

A third reason: if your haven't pumped enough to get clean seawater trickling back, you will have a mixture of urine and seawater sitting in the low points of the system - and this will cause buildup of calcium carbonate(?) deposits in the lines.

.