Am I damaging my water bottle?

I have a Hydro Flask (stainless steel) that I sip water from all day.

I like my water with a lemon slice. My question: would the lemon juice damage the stainless steel in any way?


Well I found this:

I wouldn’t worry about it but your safest bet is to contact the manufacturer.


I don’t know anything about Hydro Flask. I have worked in a few different steel mills though, and there isn’t just one thing called “stainless steel”. There are a lot of different varieties of stainless steel (varying amounts of chrome, nickel, manganese, etc), and some are more “stainless” than others. Some varieties add molybdenum which greatly increases their resistance to corrosion from acids like lemon juice.

You might try contacting the makers of your Hydro Flask and ask them what type of steel they use. If it is 300 series austenitic stainless steel for example, everything in that series contains molybdenum and will have a high resistance to corrosion from acids.

I did a very quick google search, and found this on the Hydro Flask web site:

Uh, no, it’s not the best in the business. 18/8 is type 304 austenitic stainless steel. It’s in the 300 series so it contains molybdenum. Type 316 has a higher molybdenum content and would be even more resistant to corrosion, so I would say that’s better in this application.

You’re fine, though. Type 304 has enough corrosion resistance for your lemon water.

Nitpick. 300 series is characterised by adding Nickel to the alloy. 304 has no molybdenum, it is only when you get to 316 you see moly added. 18/8 refers to the percentages of chromium and nickel.

A difference between the 304 and 316 is chlorate pitting. Above 50 C 304 can be attacked by chlorine ions - ie salt solution. Hot processing of some materials and use in marine fittings tends avoid 304 and use 316. Given most flatware is 304 there is not going to be an issue with a drink bottle. 304 is ubiquitous, but I would not have it on a boat.

Thanks, all. Bring on the lemon!

They didn’t claim it’s the best possible, just that it’s the best in use in “the business” (which we can assume is the water bottle business.) You can’t disprove their claim by showing better stainless steels exist, only by showing that another manufacturer uses that better stainless steel.

I have several stainless steel water bottles and I put them in the dishwasher even though all of them are labeled “do not use in dishwasher.” I assume they don’t want you to melt any plastic parts during the drying cycle. I don’t think I am damaging them.

Not true, unless you want to consider residual levels of molybdenum as “containing molybdenum”. Generally, only elements that are intentionally added are considered as the base composition of the material. Type 304 does not contain molybdenum in this sense. In fact, Type 316 (and its variants like 316H or 316L) is the only austenitic grade that has intentional molybdenum additions.

300 series stainless steels are those that contain enough nickel and chromium to retain the austenitic crystal structure (i.e., non-magnetic) at room temperatures. Type 304 is the standard for food service applications, and is the base composition for most other grades. Type 304 is also known as 18/8 because the basic formulation is iron with 18% Cr and 8% Ni.

Type 304 is susceptible to pitting and crevice corrosion, particularly in environments that contain chlorides. To resist these types of corrosion, molybdenum is added (at about 2%) to make Type 316. This also increases high temperature strength.

Other elements are added to other types (such as Titanium in Type 321, or Columbium in Type 347) to improve corrosion resistance when exposed to welding.

Then, there are the ferritic/martensitic grades (400 series) that contain little to no nickle and are magnetic. They are still corrosion resistant, but not as much as the 300 series types. Most stainless steel flatware is a 400 series stainless. On the other side, there are the duplex stainless steels, which slightly magnetic, as they have a mixture of austenitic and ferritic structures, but this is getting much too technical, so I’ll stop here.

I forgot to add to my previous post, in response to the OP.

No, you are not hurting your bottle with the lemon juice. High chlorides would hurt it (do not wash it with Clorox!), may even ruin it. The reason Type 304 is used so much in the food service industry is because it is resistant to both acids and bases and is easy to keep clean. Your lemon juice would remove the patina from brass or copper that helps protect the metal from further corrosion (which means putting copper into the water you would drink). Slight exposure to chlorides (such as salt water) for short period of time isn’t that bad if you rinse well afterwards, but using a stainless kettle to brine a turkey for 6 hours, for example, is likely to cause pitting or cracking.

Just check if the bottle says NSF anywhere. Or call the manufacturer. Most knives, sinks, etc that come in contact with food is certified by NSF which checks to ensure that they are non-toxic, durable, and corrosion-resistant. NSF conducts periodic audits too and has a good lessons learned system.