Raw Water Flush

Rocky Lou

Well-known member
Joined
Aug 2, 2019
Messages
413
Fluid Motion Model
C-302 C
Vessel Name
Sea Suite
Having read a number of threads on this subject, I tried using shower water to flush. Immediately, the odor that always comes after each flush was non-existent. That was great and a good workaround since it's unlikely that I'll want to switch to a fresh water system. I presumed a lot of the odor was from the foul water in my harbor and the fact the I'm near a fish processor. However, what is now puzzling me is that I spoke with a neighbor who has a larger boat and he flushes with raw water and no odor. He also spends a lot more time using his boat as a vacation home in the harbor. How can it be that he gets no odor and I do? I'm thinking it must be something to do with venting systems and he has a good one.
 
It's possible that it's what is being used with the waste in the holding tank (funky blue chemical or bacterial enzymes)?

I use Bio Clean with each flush... have for years. Absolutely zero odors. Many years ago, before I knew about bio-enzymes, I used the blue fluid and always had an odor.

One caveat, however, is that bio-enzymes don't work as well with raw water (salt water), and therefore it's less effective. I use fresh water for every flush for this reason.

Edit: I also believe (using zero expertise... just a suspicion) that the type/thickness of the holding tank can make a difference. I have found that some plastics seemingly emit the stank right through the plastic! Anyone that uses a plastic container for pet waste can tell you that no matter what you use to clean that plastic, the stank just emanates. I've stopped using plastic for pet waste and now use a galvanized canister. :mrgreen:
 
The raw water also sits in the pump and lines, and if it is saltwater and left for awhile, it starts to stink bad. I try to remember to flush my line with freshwater whenever I happen to use it for deck wash down or toilet flushing. If I forget to flush the lines after use, it stinks bad.
 
Thanks for the comments!

I'm in saltwater 100% the time, no trailer, and I'm not surprised that it's happening. I just can't figure out why it doesn't happen to my neighbor with a 42 ft. Carver, same water, same type of toilet.
 
I add some bleach to the raw water filter and flush to get it into the lines if I am letting the boat sit for a couple days in the Maryland heat. It helps quite a bit to keep the smell down.
 
Hey Rocky,
You're right regarding the use of fresh water and eliminating the smell. We switched our toilet system over to fresh water and have never had issues with the smells. We do use a RV chemical when we're actively using the tank but it can sit empty in the very hot weather here in Florida and still no oder.
We have a Raritan head and I purchased the fresh water conversion kit directly from them for something like $200, I think. It was a straight forward install, pretty easy, except of course the dreaded working in the cave aches and pains......getting to old for that anymore.
Terry
 
CaptT":1yt12v4f said:
Hey Rocky,
You're right regarding the use of fresh water and eliminating the smell. We switched our toilet system over to fresh water and have never had issues with the smells. We do use a RV chemical when we're actively using the tank but it can sit empty in the very hot weather here in Florida and still no oder.
We have a Raritan head and I purchased the fresh water conversion kit directly from them for something like $200, I think. It was a straight forward install, pretty easy, except of course the dreaded working in the cave aches and pains......getting to old for that anymore.
Terry

Hey CapT,
You got me contacting Thetford, I have a Tecma EasyFit, to confirm the part number for a conversion kit. The head has been a constant nightmare. First, the joker valve needed replacement, which should have been straightforward, but, some 'joker' epoxied all the plumbing parts together and I had to cut them apart to do the job. Then, the 2 year old pump died and this time I had someone pull the head and replace it. That job was lousy for anyone, but, being 70 I'm too old for this kind of 'thing' also.

~Paul
 
Late to the party, but instead of spending the money (and effort) of converting to a fresh water flush system, we just carry a couple of old 1 gallon plastic milk jugs filled with fresh water and use as needed. Added bonus: the weight of the jugs in the starboard lazarette helps balance the list from everything istored in the cave on the port side. Also, we recentlly started using DigestRV bio enzyme treatment for the tank. The combination is working well so far.
 
Have you tried Odorlos? It’s worked well for me.
 
Rocky Lou,

As a veteran of calamitous stink in the San Francisco Estuary, let me chime in to help out.

First, as you have probably noticed, the smell on the first flush can be gruesome. This, as noted by an earlier comment, comes from the fact that the estuary is highly productive, with lots of nutrients and critters (mostly phytoplankton and zooplankton in your case). The water from the last raw water flush you did before you buttoned up your boat stays in the lines. Aerobic decay uses up all the oxygen trying to break down all the organic stuff in those raw water lines. Then anaerobic decay sets in and you get a stinky mess when the oxygen gets used up.

So when you come back to your boat and make the first flush, all that nasty, foul-smelling organic mess goes right into your toilet before going into the holding tank. The stink can be overwhelming. Indeed, if you have someone you want to embarrass—at least in the SF Estuary—have them be the first to flush the toilet after a couple of weeks. They and all your guests will be gassed out, with most of the smell coming from the toilet, not the vent line. It is quite the conversation starter and all the abuse will be directed at the one who flushed the toilet. Add all the enzymes you want to add to the holding tank will not prevent the first flush stank. As one person noted, you can chlorinate things by adding some to the raw water strainer. I never have.

The best way around this is to go with a fresh water flush. This not only does not smell in the head, but it reduces the organic load to your black water tank. You will read some pretty elaborate freshwater flush plumbing descriptions on this site. But the simplest thing to do is just pull out the faucet on the sink, turn it on full blast spray, and push the “drain only” button sequence (hold down both buttons on our 29CB). This full blast also allows you to clean the toilet if it needs it.

Which means you have to tell your guests to let you flush the toilet for them. Awkward but necessary.

Two final things. First, if you are going to be out on the water for awhile and want to conserve fresh water, you are going to have to flush using raw water a couple of times to get rid of the smell. Once the smell goes away, just use raw water flush and you are good to go. Second, this advice does not apply everywhere. We moved our boat to Elliot Bay Seattle from Pier 39 in San Francisco. We have only occasionally had a first flush calamity and exquisite social faux pas since productivity of the waters in the PNW is so low compared to San Francisco (which is why the water is so clear). So it matters where you are. In the Delta, despite the green water with harmful algae in it, you should be fine.

Boats are just a bunch of elaborate work arounds with even more elaborate rationalizations to justify them.

Jeff
 
I'm at Pillar Point Harbor (Half Moon Bay) where the water often smells bad even before it enter the toilet system. I agree that the main problem is before the water gets to then toilet. I do add Odorlos to the black water tank and have little issue with that, it's mainly when flushing.

Using shower water does the trick, however, I may go to 1g milk cartons as was suggested.

I am surprised that no one is supporting fresh water conversation. The other FM boat owner in the harbor that I know, with an R27, converted to fresh water flushing.
 
We did fresh water conversion and would do it again. Odor is very low and manageable. We drink bottled water and use the fresh water tank only for washing, flushing, etc. That means that the holding tank always fills before water runs out, so the fresh water is not a limiting factor.

As for additives, I recommend Zaal NoFlex. It is similar to Odorlos but less expensive and easier to store.

Another minor advantage (perhaps) of fresh water conversion is that -- at least on C30 without AC -- the second raw water thruhull can be left closed unless you need the cockpit washdown. That reduces one small risk factor.
 
We did fresh water conversion and would do it again. Odor is very low and manageable. We drink bottled water and use the fresh water tank only for washing, flushing, etc. That means that the holding tank always fills before water runs out, so the fresh water is not a limiting factor.

How was the install on a Cutwater, I presume you also have a Tecma EasyFit Premium Plus which has been a nightmare for me to work on as I previously mentioned? CaptT''s post said he has a Raritan head. I've pinged Thetford for the conversion kit p/n but they have not replied.
 
Rocky Lou":22ykqwi7 said:
I'm at Pillar Point Harbor (Half Moon Bay) where the water often smells bad even before it enter the toilet system. I agree that the main problem is before the water gets to then toilet. I do add Odorlos to the black water tank and have little issue with that, it's mainly when flushing.

Using shower water does the trick, however, I may go to 1g milk cartons as was suggested.

I am surprised that no one is supporting fresh water conversation. The other FM boat owner in the harbor that I know, with an R27, converted to fresh water flushing.

I’ve had that issue too with the raw water input. In my case we went through a lengthy period with a red tide. I addressed it by doing a vinegar soak of the input hose and that worked great! The approach I used was to shut off the through hole, filled the strainer to the brim with about 20% vinegar to fresh water, flushed and then repeated until I smelled vinegar in the head. I then repeated a few more times for good measure. I then let it sit for a week. It took care of the smell!
 
+1 on Odorlos. Forgot to add it once. Stink. Pumped and then added. No stink.
 
Rocky Lou":1fn6so1x said:
We did fresh water conversion and would do it again. Odor is very low and manageable. We drink bottled water and use the fresh water tank only for washing, flushing, etc. That means that the holding tank always fills before water runs out, so the fresh water is not a limiting factor.

How was the install on a Cutwater, I presume you also have a Tecma EasyFit Premium Plus which has been a nightmare for me to work on as I previously mentioned? CaptT''s post said he has a Raritan head. I've pinged Thetford for the conversion kit p/n but they have not replied.

It was done by mechanic along with some other projects so I'm not sure of the difficulty. However I didn't hear any complaints or problems from them. (I'm personally in the camp that tries to avoid plumbing but feels fine working on electric!)
 
I also just did the vinegar flush. Used about 1/2 gal vinegar to 3 gal fresh water with few drops laundry detergent. Flushed with fresh water afterwards until it ran clean. Came out smelling like a rose!!! :lol:
 
I also just did the vinegar flush. Used about 1/2 gal vinegar to 3 gal fresh water with few drops laundry detergent. Flushed with fresh water afterwards until it ran clean. Came out smelling like a rose!!! :lol:
Can you please tell me what type of vinegar you used, household, cleaning, industrial, or something else? Another way to ask the question is what percentage was the vinegar you used which you then mixed according to your ratio of 1/2 gallon to 3 gallons of fresh water?

Thanks!
 
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