Printing on a septic system

I have what may be an odd problem: a septic tank. They don't like significant loads of chemicals or heavy metals; not only will whatever goes in the septic tank eventually leach into the yard (causing triffids to grow or whatever), but enough of a load can actually kill the biological cycle in the septic tank itself, which would be a Bad Thing.

So I'm pretty conservative about what photo chemicals go down the drain. For developing film, and even for developing prints, this isn't a big deal---I just dump into the bottles that the DIH2O came in, and make a run to the hazmat disposal every so often when the darkroom starts to get crowded with full bottles in strange colours.

But I can't wash prints that way, can I?---way too much water. On the other hand, late in the process, it seems like the amounts of chemicals coming out must be quite small, and maybe they're OK for the septic system after some initial period.

Does anyone know what I can do without drowning myself in bottled runoff water or poisoning either my yard or the septic tank?

Thanks

-NT

I am an amateur, so I am not running the darkroom 24/7. I am on a septic, and I allow some things to go down the drain, others I keep and bring to Hazmat (fixer, some developers, everything related to E-6). I don't worry about the wash water since I figure that the concentrations at that point in the process are not enough to worry about.

Kodak has a publication (J-28) which discusses disposal of the effluents from photographic processes.

Another thing that you might look into is silvergrain.org where they offer some photochemicals which are more environmentally friendly than most.

This issue has been discussed ad nauseum. Kodak even had a publication on the subject, although I believe that it added more confusion than it took away.

It is true that putting graywater from a darkroom into a septic system can create problems. But the question is - under what circumstances will there be problems?

In our former home, we had a septic tank, and I disposed of darkroom graywater by putting it down the drain.

I don't have records of our overall water consumption in that home, but I know that our total household consumption of water in 2007 was 65800 gallons. The bulk of that became graywater - through the full range of household activities (we did irrigate the lawn some during the summer months, but I don't have any way to measure how much water that entailed.)

It's a reasonable assumption that the members of our household consumed about the same amount of water in our former home, and that the bulk of that water eventually ended up in the septic system.

I consider myself lucky to be able to squeeze in one printing session a month. In addition, I may have one or two film developing sessions. Given the way I work in my darkroom, I probably generate 10 gallons of graywater per printing session, and perhaps 2-4 gallons per film developing session. Round that off to a total of 20 gallons per month, or 240 gallons per year.

Now, the chemical content of the graywater is actually quite low. I may use a gallon of developer concentrate per year, and perhaps two gallons of fixer concentrate. That means that only about 1% of the graywater output of my darkroom is something other than water, and that amounts to less than 0.005% of the total volume of water leaving the home.

Is that going to do any harm? I think not.

The point is that a realistic appraisal of the volume of liquid produced by a typical darkroom leads to the conclusion that in most cases, the amount of chemical released to the back yard via the septic tank is insignificant. Now clearly that conclusion would be different if the darkroom is used daily, or perhaps even weekly. And I would also agree that a commercial darkroom (those few that still exist) needs to take aggressive steps to address the volume of graywater they produce.

As you have noted, the major concern about the effluent from the typical black and white darkroom is the silver content in exhausted fixer. That concern can be addressed simply by precipitating the silver out of the fixer before disposing of it - just add some steel wool to the fixer, let it sit for a few days, and decant off the liquid.

And depleted selenium toner is said to be very good for roses.