Effects of B&W Rinse Waters into Septic/Drainfield Systems?

[Wayne]

A point that is not often made is that the effectiveness of a septic tank is a function of the "residence time", which is roughly the ratio of tank capacity to inflow rate. A quick Google search suggests that something like two days is a common design rule, so a 1000-gallon septic tank would be good for no more than 500 gallons per day. An archival print washer might run at 1/2 gallons per minute, or 30 gallons per hour; one wash cycle per day would correspond to about one luxurious hot shower per day, However, if the washer an continuously for six or eight hours, the impact on the septic system would not be trivial.

If prints are thoroughly rinsed first, print wash water contains negligible amounts of chemicals of any kind, and probably should be used for irrigation.

There are a dozen good points that never come up in these discussions, which are mostly filled with anecdotal but essentially useless information when applied to someone else's system. Yours is a great point that I don't think has ever come up. A corollary to that is too much water use can send solids into the drain field and clog it, also no trivial matter, though not likely to happen due to print washing alone. Another is that not all (if any) photochemicals decompose in a few days, some take up to 2 weeks. I therefore send very little into my septic, a maximum of a few liters of black and white chems (no fix; that goes to a photo lab) per week. There is no real quantitative science behind that amount; its just the most I'm comfortable with and I'm not suggesting anyone follow my lead. My darkroom isn't even hooked up to my septic. My rinse and wash water goes straight into the yard and I don't think twice about it.

[Wayne]

Rid-X

Think of it as insurance.....

Think of it as covering up septic problems you don't want to cover up. Everything you need for proper septic functioning goes in when you flush human waste.

[Michael Rosenberg]

I have been on a septic system for 15 years now, without ever having a problem. I am a fairly heavy user of my darkroom, especially since I retired 10 yrs ago.

I do the same as what Doremus does, except for recovering the silver with a silver magnet. I then poor the exhausted fixer down the drain while washing prints as to dilute it. The developer is pretty exhausted when I am done, and I pour the stop bath in with it before dumping down the drain. I check the pH with pH paper to make sure it is under pH 8. When I bleach with KFecyanide I neutralize it with fix, add steel wool, and let it evaporate in a wide mouth jar. Eventually I will take it to the local county dump household waste dump.

The print wash water is very dilute, and nothing toxic (i.e., high quantity) is present with the amount of wash water I use.

Note, fixer has the same chemicals as fertilizer. The biggest danger causing the bacteria to rapidly grow consuming too much oxygen, then dying off.

Mike

[Harold_4074]

Note, fixer has the same chemicals as fertilizer.

I wish that I could be sure this would always be true, particularly for TF-4/TF-5. I don't think I've seen an alkaline fixer formula that doesn't contain borate (although some say that it can be replaced by bicarbonate) and boron is definitely not a fertilizer ingredient in my neck of the woods. In fact, the local water has enough boron to give some plants (azaleas, for sure) trouble.

The ammonium thiosulfate component would be a good nitrogen source, and I doubt that the sulfates would do any harm above and beyond what is already in my water.

I wish I knew how to formulate an archival fixer based on ammonium thiosulfate and potassium phosphate---with an N-P-K ratio of about 5-10-5

[Richard Wasserman]

[I]
I wish I knew how to formulate an archival fixer based on ammonium thiosulfate and potassium phosphate---with an N-P-K ratio of about 5-10-5

Does this meet your needs?

I use Ryuji Suzuki's Neutral Rapid Fix

Ammonium Thiosulfate 60% 200ml
Sodium Sulfite 15g
Sodium Metabisulfite 5g
Water to make 1 liter

[papercam]

CUT-SNIP-PASTE

Note, fixer has the same chemicals as fertilizer.

[..............] and boron is definitely not a fertilizer ingredient in my neck of the woods.

not mine neck of the woods neether!

[liminals]

there are test kits you can get that will tell you how much silver is left in your wash water too
so if you wanted to, you could see for your situation what was there..

I'm trying to find one of these online - would you just use a residual silver test kit like the one Photographer's Formulary sells? And drop it into a sample of the wash water instead of on a test print?

[Jim Noel]

I know a well known Fine Art Photographer who used to have an apple orchard. He ran a hose from his darkroom into the orchard. It was moved to a different tree every day, the apples flourished and were delicious.

[Harold_4074]

[I]"would you just use a residual silver test kit like the one Photographer's Formulary sells[/I"]

Well, I wouldn't---the test kit is designed to make a solit deposit visible against a reflective background--presumably printing paper. A drop into a sample of water might just give slightly tinted water, independent of the silver content.

In any case, even if there is silver in your wash water, it will almost certainly end up in the septic tank sludge, not the leach field. Septic tanks normally have a lot of ammonia and hydrogen sulfide in them. Wikipedia thinks that the solubility of silver sulfide in room-tempeature water is 6.21 x 10^-15 grams per milliliter, and that it is insoluble in "aqueous ammoniums" (presumbably ammonium ion in water).

Or you could plant some apple trees and irrigate....

[jp]

If you're developing film, there is little reason to waste a ton of water... Just change the rinse water a few times over the rinse time rather than run the water continuously.

(I have a septic system and dump everything down the drain; I choose not use dichromates of any sort because I don't want to be dumping them into the ground)
Growing up I had a basement darkroom and let everything run down the basement drain rather than septic system because it was easier.