Marine Head Backflow

[dsiekman]

I've noticed an "interesting" smell on the boat this year and think I have finally found it. It appears that the head will not completely dry flush. I do not have much experience with marine heads but understood you first wet flush to clean the bowl then flip to dry flush to remove all water and seal off the outlet. What I noticed last night is that upon dry flushing, all water would leave the bowl only to return a few seconds later. According to the tank monitor the tank is only half full. Could I have a clogged vent or air lock somewhere? Have I created a siphon through the sea ****? Am I up **** creek without a paddle? (Sorry, couldn't resist) Thoughts?

 

[shrew]

Re: Marine Head Backflow

Here is what I do which leads to zero head odors. First, keep in mind that there is a hose that goes from the head to the holding tank. When you dry flush, you are only discharging from the head to the sanitation hose, not the holding tank. The valve on the pump of the head is what keeps the contents from backflowing back into the head. These valves rarely work very well, even on brand new heads (I replaced mine 2 years ago and brand new head still does it).

1) If we're kicking around drinking beer and the head is beign used frequently, then a dry flush followed by a few pumps of wet flush is fine. However at the end of the day, I pump enough water in to completely push the contents of the head and sanitation line all the way to the holding tank so that all that is in the sanitation line is freshwater.

2) At the end of the weekend, I pump out the holding tank, regardless of how full it is. I then pump 3-5 gallons of freshwater into the holding tank after the pumpout to 'flush' the tank, then pump that water out as well.

3) I use about twice the amount of holding tank chemicals than is recommended. I put some water in the system, then the chemicals, then more freshwater to pump the chemicals past the sanitation line and into the holding tank. Again, all that is left in the lines is freshwater.

The key to make sure that the contents of the holding tank are pumped frequently. I don't leave contents in the holding tank for more than 3-5 days. If I'm leaving on a Sunday and won't be back until Friday, the holding tank gets pumped out as described. You don't need to pump enough water to flush the entire santiation line for EVERY flush, but make sure it is done at the end of every day it is used, and don't leave contents in the holding tank from week to week.

This ensures you're tank is always empty when you take the boat out and should always smell good.

 

[soggy_feet]

Re: Marine Head Backflow

Same problem here, and my fix was to do a pretty good flush of water to clear the line, but then I don't bother with the dry flush. That part depends on your boating. My boat doesnt rock enough to worry about bowl water sloshing (the main reason, I believe, for the dry flush), and after noticing that it only back flows a couple inches, a couple more inches of water left in the bowl is enough head in the head line to keep it from leaking back.

I also use copious amounts of chemicals.

 

[dsiekman]

Re: Marine Head Backflow

Thanks, guys. What's wierd is that I would swear last season it stayed dry.