Adding Bleach to RO Water

[sailorboy1]

Interesting thread drift

But I will rephrase the question “are people concerned about flushing their watermaker, through the carbon filter, using water with normal drinking water levels of chlorine in it?”

[garychurch]

Interesting thread...

As far as I know the water from my RO Watermaker is slightly acidic, a ph of about 6.5 compared to commercial supply which is nominally 7.5 (obviously depends on source).

This acidity causes a slight calcium buildup from a reaction to the aluminum water water tanks over time.

Our system also has a periodic backflush from our water tanks. According to our manufacturer nothing should be added to this backflush because it could affect the watermaker membranes in a bad way.

Bottom line for me is not to add clorine to the water tanks nor any other additive. We don’t have an algae buildup because we run a lot of water through our system as a live aboard.

Just my perspective on the topic.

[Crusty Joker]

Most municipalities and water companies that provide potable water using available chlorine want to maintain 10ppm available chlorine at the tap.
There are other systems to provide potable water that is acceptable for drinking and food processing. Deionization and Ozone generators are a couple of others. I do not know the applicability of those systems to water makers on board. Water testing can use many methods to determine safety and suitability for purpose. Long term storage may be a challenge as is reuse of water or treatment of water from variable sources that may contain a variety of contaminants. Rio Dulce water is challenged by stagnation and presence of pathogens and also petroleum storage and use. There also may be contamination from a variety of marine paints, haul out yards and industrial and agricultural sources. I was there for a month and after 2 years still have lingering health issues. Never plan to return. The tropics I love dearly, but not all water making and purification systems are created equal...
Now, back to my still.... a drop of the dew?

[Cheechako]

Why use bleach if you have a watermaker..? Am I missing something?

[sailorboy1]

10ppm?? at the tap, you better look at up because that is Legionella disinfection level an way beyond drinking water.

But it is thread drift as the thread is about a watermaker membrane

[Crusty Joker]

I will add to my post and the wisdom and EXPERIENCE of others that a test kit is very cheap... just use the dip paper. Lasts a long time but keep it dry.

[sailorboy1]

Originally Posted by Cheechako

Why use bleach if you have a watermaker..? Am I missing something?

For same reason you add it to any water

[Dsanduril]

Originally Posted by tkeithlu

"To disinfect a storage tank or other large volume of water, thoroughly mix non-scented NSF-approved household bleach (5.25% chlorine) in the reservoir at the ratio of 1 gallon of bleach for every 1,000 gallons of water (i.e., 1 quart for every 250 gallons of water). This will give a chlorine concentration of 50 ppm."

Compliments of the State of Idaho.

50 ppm is used to disinfect a tank, not to disinfect drinking water contained in a tank. Once you disinfect the tank you drain the highly chlorinated water out of the tank:

Add bleach directly to the storage tank at the same time you are disinfecting the well. Let the storage tank drain into the distribution system. After sitting 12 to 24 hours, drain the storage tank through a drain valve or through the distribution system. Do not dispose of chlorinated water on vegetation or into surface water. https://www.deq.idaho.gov/media/5176...sheet-0612.pdf

Originally Posted by Crusty Joker

Most municipalities and water companies that provide potable water using available chlorine want to maintain 10ppm available chlorine at the tap.....

The EPA MRDL (Maximum Recommended Disinfectant Level) for Chlorine and Chloramines is 4ppm. European standards for chlorine are generally lower. The WHO recommends a maximum limit of 5 ppm.

To Sailorboy's original question. We do not regularly add chlorine to our tank, but it does get chlorinated from time to time. About once a year we disinfect the tank at levels similar to the 50ppm described above. We then discharge that water through a carbon filter (because it usually goes overboard). We occasionally put city water in the tank which has chlorine and/or chloramines. We trust the properly maintained carbon filter on the watermaker flush inlet to remove the small amounts of residual chlorine and protect the membrane.

I don't fret about it much but do make sure the filter is maintained. If we have just disinfected the tank I do make sure we have flushed a fair amount of water through the tank before using it to flush the watermaker. We do use the pool test kit as described above to make sure we're not feeding 50ppm chlorine into the watermaker flush filter. We do not bother to make a separate bucket of RO water for WM flushing. YMMV.

[Scubaseas]

Originally Posted by sailorboy1

I think i wasn't clear . The question is about adding bleach to your water tanks then using that water through your watermaker carbon filter to flush the watermaker after use or as needed.

Yes I use bleach and yes I run the flush water for the watermaker through a carbon filter before it hits the membrane.

But then I am toying with filling one tank with Gin and the other tank with Tonic lately.

[John De Bree]

I must be missing something too. Because here in Australia a lot of us non city people in the country are on rain water tanks and we never add anything to our water. And it's the same thing on my boat every 10years like at home we wash our the tank. We all seem very healthy so I'm confused why you want to put anything in at all.

[Scaramanga F25]

Drops of Iodine is better'

[Leee]

Careful with chlorine if you have stainless steel water tanks though. Pinholes will appear and are they ever hard to find! Took me a whole summer to find one that had been in an easy part of the tank to see.

[Stewie12]

I would only use product water to flush the water maker as the membranes will be ruined with bleach, and they are expensive rot replace. Not worth the risk.

[Mike Banks]

You can also use Milton tablets. One tablet in 2 litres of water, then toss this two litres of pre-mix into a tank at the ratio of about fifteen to twenty to one--ten to one if the water is doubtful--and leave it for a few hours to do its job. It is sold as a sterilant for baby bottles--but it is just sodium hypochlorite in a tablet of measured amount. Not cheapest way of doing it--but convenient.

[sailorboy1]

As the OP I guess I need to just give up on the thread. For some reason it has become a “how to disinfect a water tank”