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Salish Sloop 18-06-2018 09:28

Flushing w/ bleach - environmental concerns?
Hi all,

Unfortunately we've allowed our fresh water system to become completely gunked up. We don't drink from our tanks, but I'd like to be able to use the water to wash with when we're out cruising. We have plastic tanks, 25 gal and 18 gal, and they are pretty inaccessible without dismantling major parts of our cabin which rules out scrubbing them out. Our next thought was to flush the system with bleach solution and I've been reading about procedures for doing that - however, if we fill our tanks with bleach solution, how do we drain it out? all of our sinks drain directly into the ocean. I am concerned about the environmental impact of discharging bleach solution, since even a small amount is harmful to marine life. Plus, it's against the rules in our marina. Do folks wait until they are hauled out and then discharge into a bucket? flush into gray water holding tanks and then pump out? Or discharge directly overboard?

I know about sanitizing alternatives but have the same environmental concerns about some of those. My previous "environmentally friendly" solution - white vinegar - didn't do the trick and stuff is still growing. I feel like I must be missing something and there must be a way to do this, but I just can't think of what it is! Any advice is much appreciated :)

Thank you!!

svHyLyte 18-06-2018 10:13

Re: Flushing w/ bleach - environmental concerns?
Try Trac Ecological's PSR. Non-toxic and works well.

a64pilot 18-06-2018 10:21

Flushing w/ bleach - environmental concerns?
Bleach if not used in excessively strong concentrations is not all that bad really, there is bleach (chlorine) in your municipal water system, and swimming pools of course.
Donít go overboard with the bleach, it only takes a little bit.
Why are you not drinking out of your water tanks? What are you going to drink from?

peghall 18-06-2018 10:36

Re: Flushing w/ bleach - environmental concerns?
Chlorine/bleach does no harm to the environment because it evaporates very any swimming pool owner will confirm.

Over the years I've posted instructions several times for recommissioning a fresh water system (they're also included in my books). If you can't find 'em, send me an email or a PM that includes your email address (no way to attach anything to a PM) and I'll send 'em to you.

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

Salish Sloop 18-06-2018 10:47

Re: Flushing w/ bleach - environmental concerns?
Thanks for the advice and resources! Yes, I've read conflicting things about bleach. Some folks have said it's not all that harmful and breaks down/off gases quickly. Other resources say even tiny concentrations are destructive to marine life. I would be inclined to do it just this once, but want to make sure I've exhausted all other available options.

We don't drink from our water tanks because we don't liveaboard and don't cruise for more than a week or so at a time, so we just bring along a 2.5gal refillable container for our drinking water. I don't think I would want to drink from the tanks without being able to even see, much less clean them out first. But I would love to have water without visible clumps of algae in it at the very least :smile:

Ken Z 19-06-2018 08:24

Re: Flushing w/ bleach - environmental concerns?
I wouldnt worry about bleach in limited doses, but I then flush with rubbing alcohol for a final clean out, about a pint to 20 gal. of water, and pump it through my hoses. Too much bleach in your bilge can wipe out your bilge pump.

cptandy 19-06-2018 08:25

Re: Flushing w/ bleach - environmental concerns?
I am the business of removing mildew from sails and canvas and we use a fair amount of Sodium Hypochlorite known as bleach.
We reuse the solutions for a long time but when discharging we simply add a small amount of Sodium Bisulfite, which completely neutralizes the "bleach".
It is the same principle used in fresh water aquariums when changing the water and it is obtainable from most pet stores.

flyingfin 19-06-2018 10:17

Re: Flushing w/ bleach - environmental concerns?
Yes, chlorine residual in water can kill marine life. However, the concentration of chlorine is critical and whether or not it is fresh or salt water. But you dont need to create a lot of wastewater. Suggest you drain tank, fill with 5 gallons of fresh water, super-chlorinate with one quart of household bleach, then go out in rough water and get it sloshed around and all debris in suspension. Remove sink drain pipe and empty it into a few 5 gallon buckets so you can inspect the water quality and carry the buckets ashore where you can empty it into toilet.

Cheechako 19-06-2018 10:31

Re: Flushing w/ bleach - environmental concerns?
Wouldn't worry too much about it. The bleach is very diluted by the time it reaches the water around your boat.

Snore 19-06-2018 11:11

Re: Flushing w/ bleach - environmental concerns?
First if you are using CL whatever you are cleaning will eat up most of the CL.

For the truly OCD the industry standard way of avoiding impact is some sodium thiosulfate.

Cadence 19-06-2018 12:14

Re: Flushing w/ bleach - environmental concerns?
Pump it overboard and don't worry about it.

jkindredpdx 19-06-2018 17:49

Flushing w/ bleach - environmental concerns?
Just to be safe I splash some whisky in my glass of drinking water.

Dsanduril 19-06-2018 18:02

Re: Flushing w/ bleach - environmental concerns?
You could also buy a $10, 10-inch carbon filter, pump out through the carbon filter, you'll be discharging bleach free water until the carbon filter loads up but should be able to get one cleaning session completed. Drop the used filter in the local solid waste disposal system.

If you discharge without removal if there is any remaining free chlorine (and there should be, otherwise you haven't completed the disinfection of your tanks) then you will kill some of the small organisms in the saltwater at your point of discharge. That is the point of the bleach after all, killing the small organisms. The action of bleach as a disinfectant is a chemical oxidation, so the bleach is used up in the killing action. There is no long term residual effect, once the bleach is used it becomes inert. But, you will create a small 'dead pool' of bacteria/algae/etc. at your point of discharge. You decide how critical that is to you.

SqPeg 21-06-2018 08:12

Re: Flushing w/ bleach - environmental concerns?

Originally Posted by svHyLyte (Post 2654502)
Try Trac Ecological's PSR. Non-toxic and works well.

Wow! $78 gal.

CarlF 21-06-2018 08:54

Re: Flushing w/ bleach - environmental concerns?
Remember that the municipal water that everyone in your marina is using to wash down their boat has chlorine in it. Dilution is the key.

Try using a weaker bleach solution and see if it works. 1/2 tablespoon of bleach in 25 gallons is about pool strength (3 ppm). So try a few tablespoons of bleach instead of the full shock. And after it's clean, get in the habit of adding just enough bleach so that you can smell it - maybe a teaspoon - once a month. This will avoid a repeat.

Also, go to your local pool store and get some spa cleaning chemicals (same as for pool but in smaller packaging). While the bleach will sanitize the tank it won't necessarily remove all the stains and crud.

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