UV lamp before the water faucet : when should it be turned on ?

[redsky49]

For sterilization, 50ppm chlorine for 24 hours, or 200 ppm for 4 hours. That is the US standard code requirement for every municipality, as far as I know.

There are several harmful bacteria that are worrisome, Legionella pneumophilia for example, that can resist standard treatments, but we are really headed down the rabbit hole on this thread.

For a practical approach, the filtration systems mentioned above, along with boiling water in extreme cases, is more than adequate.

Stainless steel is not as reactive to chlorine as aluminum. Reasonable concentrations of chlorine are not an issue.

Chloramines are the umwanted byproduct of misused chlorine, as well as cloramides.

We sailed for a year in the Bahamas with an 18 month old several years ago. Kids are resilient. New parents tend to worry/overthink. Exercise normal common sense. You will be fine.

[JstaRebel]

Originally Posted by toddster8

OK, Chlorination by-products. I wasn't going to delve into that, but chlorine will react with organic matter, especially in an acidic environment, to produce a variety of volatile halo-organic compounds. Some of these can be toxic or carcinogenic, but the concentrations are usually less than 1 ppb.

They are very easy to detect though, if you have an electron capture detector (as I do) and can look quite alarming. Municipal water might have three or four halomethanes, while samples from home chlorine-drip systems might have a hundred different peaks, most of which I can't identify. Usually at much higher concentrations than the municipal samples. The good news is that these can be pretty much eliminated by absorption onto an activated carbon filter. The bad news is that filter will then add more bacteria to the water. You just can't win.

BTW, you get these compounds in sea water, too. But swimming pools will have a true witches brew of chlorinated volatiles, at thousands or millions of times greater concentration. And nobody is exactly sure why pools with similar systems will have different by-products. But lot of it probably has to do with the amount of urine in the water. (I've had samples from one high-school pool in CA with potentially toxic concentrations of chlorate. It's a bit like carbon monoxide poisoning, except you can become acclimated to it. But the visiting team will feel fatigued, run-down. (Could they be doing it on purpose?)) But I digress.

Oh, and BTW, Giardia and Cryptosporidium are not bacteria, and they, and Pseudomonas, can certainly get into your tanks if the hose at the dock is fed from a diverted creek or open reservoir somewhere and not pre-treated.

Regarding chlorine by-products​, rather than get into a long drawn out discussion, I shall just say that I always use and have posted in this thread to follow up with carbon block filtration which will pretty much take care of any by-products . Thank you for pointing out that Crypto and Giardia are pseudomonos. That's pretty much why I included them all together.

Look. Use what you want. I don't​ care. I make my own water, and chlorinate my tanks with a carbon block afterwards. I've done water treatment my entire life and know what works, what doesn't, and why. BTW, I also hang a nylon sock with Calcium Carbonate chips in my tanks to add some alkalinity to my starving SWRO permeate. But I'm sure that you or many others dont. However, how many of you get discolored water from your water heater if water has been sitting in it for awhile? Ever wonder why?

[redsky49]

[QUOTE=J....However, how many of you get discolored water from your water heater if water has been sitting in it for awhile? Ever wonder why?[/QUOTE]

Extremely pure water, measured by electrical resistance rather than ppm, is frequently referred to as "hungry water". This due to the tendency to ion bond with its piping/containers, etc. It will react with many materials and turn very interesting colors.

[papalagi]

If you have a holding tank for the tap water with an UV-lamp that cover your daily consumption, 10 min an hour would be more than plenty. When preparing the RO-water for a biotechnology lab, the UV-lamp in the holding-tank is typically set to a 10 to 20% duty-cycle. Eg. 10 min/h. In practice preparing drinking water, far less should be necessary. 10 min once or twice a day should be more than enough, better than bottled water anyway. There are far less nutrition for the bacteria to grow on in the already filtered water.

[JstaRebel]

Originally Posted by redsky49

Extremely pure water, measured by electrical resistance rather than ppm, is frequently referred to as "hungry water". This due to the tendency to ion bond with its piping/containers, etc. It will react with many materials and turn very interesting colors.

SWRO permeate water is NOT extremely pure water and in fact it is only pre treatment to achieve extremely pure water which is measured at 18.3 megohms resistivity from mixed bed Deionization. RO water won't even register close to 1 megohm and can't be read in "resistance" just conductivity or uS/cm (microsiemens). The issue is that SWRO water is imbalanced and literally has no alkalinity. So you give it a Tums or Calcium Carbonate to help satisfy it's aggressive nature. Large systems on island resorts use huge upflow tanks filled with sacrificial Cac03 and most follow up with a polyphosphate blend injected into the post treatment do detur the aggressive nature of the permeate. Larger systems such as the ones found on the island of SXM, Tortola, St. Thomas, Curacao, Trinidad and such use lime softening process to add sufecient alkalinity and neutralize the waters aggressive nature. The point is that post treatment is necessary in these situations. On a boat not so much unless I was using metal storage tanks. Then I would be doing something about it. Again.. use whatever makes you feel safe. Some guys like all chain, some think 100ft. with rode attached is good. Some guys like multi hulls, and some mono's. Same goes for your water. You feel safe with UV, use it. Think a filter and a little bleach in the tank once a week is good? Ok. Think that the RO itself is perfect.. That's good too. Whatever floats your boat cause none of it is going to kill you.