My municipal water department tells me everything that is in our water in ppm but does not mention Ph, anywhere. As I know Ph makes a difference in developers, and I also know that hardly any two municipal water supplies are the same. I would like to know if the city water is: acid, neutral, or alkaline. What is the best way to find out? I am using distilled water now but would like to use filtered tap water for stop bath and fixer sometime in the future. Thanks...Richard.

Google for litmus strips or ph test strips. Amazon has a ton for under $10/pack.

Not to discourage you, but tap water has almost no buffering capacity, and will not affect the final pH of your developer.

Think of it like throwing an ice cube into an olympic swimming pool. Would this change the temperature of the swimming pool? Yes, but not enough to measure.

Even if your water is something crazy like pH 5 or 9, it has no buffering capacity, ao when you add the acids and bases

present in the developer, they will totally overtake the small acidity/basicity in your tap water.

Another way to think of it: your stomach acid is on the order of pH 2, but it doesn't change very much when you drink a glass of water.

ppm is "parts per Million". So if you have 100 ppm of something in the water, it is 0,1 g/l. Quantities in this range have an effect if it is phenidone or copper ions, but usually do not affect the ph very much. The ph of tap water should just a tad above 7, neutralization and adjustemnet is standard practice. (This does not apply if your tap water comes directly from a well, of course.) The ph of standard tap water will have no visible effect in a normal darkroom as the quantities and buffers used for developer / stop / fixer are significatly bigger & stronger.

What are you planning to do? For emulsion making, stay with distilled water, for printing and negatives, tap water in most cases will do.

Years ago a friend went to Art Center (at that time in Hollywood, CA) and completed the two year professional photographer's course. At the school, developers were mixed using "tap" water. It evidently was acidic. When he came back here, he mixed his developer using our water which is evidently on the alkaline side. The first films he developed back here were over-developed. He was shocked and upset until he realized that it must be the ph of the water that he was using and corrected the developing time. At that time Art Center was teaching the zone system (that is where AA and Fred Archer developed it) and my friend used + and - in his commercial photography and the ph in the water definitely made a difference. There is another city south of here where the tap water is so alkaline that I do believe you could develop film in the tap water alone. In my darkroom, all of the tap water its filtered to rid it of particulate matter. For mixing developers, I guess I'll stay with distilled water. I may go with filtered tap water for acid stop and plain fix which I understand is a bit alkaline also.....Thank all of you for your advice............Regards!

iandvaag said:

present in the developer, they will totally overtake the small acidity/basicity in your tap water.

Another way to think of it: your stomach acid is on the order of pH 2, but it doesn't change very much when you drink a glass of water.

Click to expand...

It is off the subject, slightly but I was taught, I think in organic chemistry, the when a weak organic acid like acetic or citric comes in contact with a strong acid, like the hydrochloric acid in the stomach, they act as buffers and act like bases and are therefore good as antacids.. Wonder if that is still true?..........Regards!

Tap water being acid usually is a huge problem for the water company as this will destroy the water & sewage lines, besides the desinfection of the water with sodium hypochlorite is not possilbe any more. Public water suppliers generally try to avoid this situation and adjust the ph within the range 7,1-8,5. Some places might differ, and if you are on your own well things are completely different.

One comment on pH: It is not just the absolute number that matters, but also where it comes from. You can reach a high ph with a very small amount of sodium hydroxide: 1 g (0,025 mol) NaOH / 1 l H2O will give you a pH of 12,4. This pH is too high for most photographic purposes, but at the same time the quantity of OH- available is small. 106 g (1 mol) of Na2CO3 / 1 l H20 will give you a pH of 12,2, but you have a long lasting supply of hydroxide. So it is not the ph alone that matters.

I don’t intend to be antagonistic, but I have a few more comments I hope are helpful:

Developers are not simple alkalis, they are reducing agents which become more active at higher pH values. I’d be quite surprised if you could develop film in potable tap water.

Water can have an effect on developers, but generally not because of its pH. RauschenOderKorn's comments are correct; measuring the pH of water will not tell you very much. pH is simply a measure of the H+ ion concentration in the water. It doesn’t tell you how easy or difficult it is to change the H+ concentration.

You can easily do the experiment yourself. Mix up a litre of D-76 (or your favourite developer) with tap water from your city and measure the pH of the solution.

Now, go visit that city south of you with the crazy high alkaline water. Mix up a litre of D-76 using that water, and measure the pH of the solution.

If you measured carefully, I can tell you now that these two developer solutions will easily be within 0.1 pH units. How is this possible, given that the pH of the water you started with might be different by 3.0 pH units or more ?! The answer: buffer capacity. Developers contain acids and bases which form a buffer solution when dissolved together. This ensures that the developer solution will have the proper pH regardless of the pH of the tap water.

If you used water that was buffered, the developer would not come out at the correct pH. But potable water has a negligible buffer capacity.

You mostly recalled correctly from your organic chemistry course, a buffer solution can be made by mixing:
A) a weak acid with a strong base (e.g. acetic acid and sodium hydroxide for buffered stop bath), or
B) a weak base with a strong acid (can’t think of any photographic solutions that use this method)
C) a weak acid and its conjugate weak base (e.g. boric acid and borax, like in Ilford ID-68)

All the best in your efforts to achieve consistency.