Reverse Osmosis (RO) Water vs Distilled Water for Film Processing

[kozesluk]

London (very hard water) user here - I use RO for everything (mostly for coffee). I have built my own system. Works nice for photographic chemistry, especially final rinse doesn't leave any marks at all. I use tap water for washing.
If you want RO for this and also maybe for drinking look at Ecosoft products - they offer much better value than Everpure. I do install a lot of their RObust PRO/Coffee systems in various places (professional coffee machines engineer/technician). Uses non-proprietary filters and membranes.

 

[mshchem]

I have a whole house water softener in addition to the ro systems. Soft water is required for American dish washers as no built in softener, also for laundry and bathing. The softened water has so much sodium carbonate it's useless for m8xing certain developers. I use hard water for all outdoor sill cocks.

 

[farpointer]

Troop and Anchell seem pretty insistent that distilled/filtered water is necessary to prevent early failure in developers like XTOL. Is that just speculation on their part?

 

[koraks]

Troop and Anchell seem pretty insistent that distilled/filtered water is necessary to prevent early failure in developers like XTOL. Is that just speculation on their part?

This relates to the presence of esp. iron ions in the water that will trigger a fenton reaction that progressively destroys the ascorbate in the developer. This is well documented. For factory-made XTOL, this is likely not really an issue (as long as the manufacturer's storage lifetimes are observed) due to the inclusion of effective chelating agents that bind the iron so it becomes harmless. For DIY derivatives of XTOL that leave out these chelating agents, this can and indeed will be a problem, but it can be avoided by using the developer immediately after mixing it and discarding it thereafter. Given the low cost of the ingredients and the low environmental load posed by them, this is a feasible solution.

 

[mshchem]

One thing. RO water uses a lot of water to do it's job. If you live in a place with natural soft water, like much of the northeast US you really don't need anything from a household and photography standpoint. In areas where water is scarce RO systems may be illegal.

When I first moved to the country and was on community water I was shocked. So much crud in the water couldn't dissolve developer with a lot of sulfite.

 

[Bill Burk]

I once bought a RO unit for home use. We used it for water pitcher purposes, tea and coffee. It lasted a long time but eventually burst a second filter casing and I decided to retire it. We used Britta now in the house.

I used RO only for the gallon of water to mix chems from powder and the final rinse. Used plain tap for the 1:1 mixes, stop and wash.

 

[DDTJRAC]

Hi everyone,

I was wondering if anyone here has experience with reverse osmosis (RO) water filtration systems, particularly the Everpure MRS-600HE-II. Is it worth investing in one when processing high volumes of film daily? How does RO water compare to distilled water?

If so, which parts of the process is RO water typically used for, and how often are the filters replaced in practice? I understand they’re generally changed about every six months, but I’d love to hear how this works in real-world use.

Thank you very much!

I've tested water all across America, more or less. RO is definitely not just like distilled, but it is very clean. RO seems to be about 95% as good as distilled, but just going by the test photos. Nothing scientific here. It may be only 89% as good...dunno, just guessing.

Here are the test photos...you check it out. Lots of RO tests there. See the bottled water section.

Distillation residue from 1 gallon of Richmond, IN tap water

NSFW

Distilling water is a quick acid test you can do to find out what residue is in your water.

No…it is not recycled motor oil. It is the distillation residue from 1 gallon of Richmond, IN tap water. Article Dedication in Honor of Alfred Eisenstaedt & Andreas Feininger Selection…

danielteolijr.wordpress.com

 

[koraks]

Did you crystallize it out and smoke that @DDTJRAC ?

 

[titrisol]

At my grandpa's we had very hard water (hard rings in most pots after a while)
He used to boil water to use in photographic solutions and distilled for final rinse.
His negatives from the 40s onwards are still looking good

But nowadays a softener or a RO system would be easier.

PS once I left a soup bowl full of water before we left for school and when we came back 2 weeks later the bottom was covered in crystals. I wished my dad took a picture of that.