How long star-san will last in a Keg?

Hello I know this have been ask 1000’s times before. But I have 5 gallons of star-san make with Distilled water an I have in my 5 gallon corny keg an I purge the 02 out with co2 but i did not leave co2 pressure on it just enough to get the 02 out of there because I don’t want my star-san to become carbonate… Now here the ? long will the star-san last in my keg …

No reason to purge it, you can just store in the stainless. But a bucket would probably be more useful - you can just drop your hoses and smaller pieces and jars, etc., into the bucket and fish them out, can’t do that in a keg.

Shade, how long would you leave and reuse star san that might be kept in a 5g bucket w/ lid?

[quote=“Steppedonapoptop”]Shade, how long would you leave and reuse star san that might be kept in a 5g bucket w/ lid?[/quote]Depends on what I’m doing with it, but typically it’ll last a couple months - every now and then I’ll decant off the accumulated debris to a fresh bucket, rinse out the original, pour it back, and top off with fresh water and a splash of StarSan, then check the pH to make sure it’s <3.

You can get some pH strips to test it - 3.5 is the top end for its effectiveness. Cloudiness may indicate some degradation, but the pH is the key, as it is an anionic acid. I have kept it for months when mixed with distilled water.

I’ve gone a month without testing. The cost is not so important. 2-3 uses then dump.

[quote=“Steppedonapoptop”]The cost is not so important.[/quote]Yeah, it’s not a cost thing for me, I buy it by the gallon, it’s just more convenient to topoff as needed rather than getting a carboy of fresh water every brewday.

+1. I do this, myself, mostly to get rid of the unslightly accumulated debris at the bottom. I also avoid using it to “wash” (aka store) dirty brewday materials, to promote longevity.

Keep in mind StarSan can pit stainless, so storage in a keg is not the best way. A plastic jug is better.

Also, most people don’t need to make up 5 gallons for any reason, ever. You don’t need to submerge things to sanitize, just get them wet. I make up 1.25 gallons at a time at most. Usually don’t need more than that, and that gets tossed the next day except for a spray bottle’s worth.

Ruhooo Roscoooo. I’m going to have 16 kegs rotting away then… I keep about a gallon of starsan in every keg when in storage. Every now & again I give them a good shake when I walk by.

Is it possible you are thinking about chlorine? That will pit Stainless steel… :wink:


I tested a 3 month old batch of StarSan made from RO water and it came in at 2.4 PH. It was fairly dirty looking and I had been using it to clean just before putting the equipment away.