Setting up the kitchen
what actually needs replacing, and what the testing says about the restEveryone arrives at the same question in the first week, usually at about eleven at night: can I just use the same knife if I wash it properly? The advice you find is mostly lists of things to throw away, written with great confidence and almost no numbers. There are some numbers. They are worth knowing, and they aren't the whole answer.
What was actually measured
A 2024 review in Nutrients pulled together the studies that tested shared kitchen equipment and measured what ended up in the food. Against the 20 ppm threshold that gluten-free labeling uses:
Gluten-free bread toasted after regular bread came out at 5.1 to 8.3 ppm. Under the threshold.
Draining gluten-free pasta in a strainer just used for regular pasta stayed under 20 ppm.
Under 20 ppm.
Cutting gluten-free cupcakes with a knife just used on regular ones: 2 of 28 samples came out over. So mostly clean, and not always.
33.9 to 115.7 ppm. Five times the threshold at the low end. This is the one that fails badly.
Fries cooked in oil previously used for breaded food: a quarter of samples over, some above 80 ppm. The other one that fails.
So the answer to the knife question is mostly yes, and the honest version of mostly is 2 out of 28. Which isn't nothing when the thing being measured is your kid's intestine.
The two that genuinely fail
Notice which ones those are. Not the toaster everybody argues about. The two failures are both liquids that other food has been cooked in, and both are invisible: shared pasta water and a shared fryer.
Water is the one that surprises people, because it looks like water. Pasta sheds gluten into it, the water goes cloudy, and then it coats whatever you cook in it next. Cook the gluten-free pasta first in fresh water, or cook it in its own pot. If it's already happened, rinsing the pasta under running water brought the samples back under 20 ppm, which is genuinely useful to know at dinner time. Under 20 ppm is still a labeling threshold and not a promise about your own child, so plenty of us would tip that pan out and start again anyway.
The fryer isn't fixable. Oil that has cooked breaded food is contaminated for as long as it is in there, and no amount of asking nicely changes it. It's why a restaurant saying the fries are gluten free isn't the same as the fries being safe, and it's the question worth asking before any other.
What we replaced anyway
We went gluten free across the whole kitchen rather than running two of everything, and low numbers in a lab didn't stop us throwing things out on the way. The pattern is porous and grooved: anything gluten can get into and not come out of.
Wood is full of tiny channels, and a scratched board has even bigger ones. They're cheap, so they get replaced rather than scrubbed harder.
Once a nonstick surface is scraped or flaking, the grooves hold on to whatever was cooked in it. Worth replacing for its own sake anyway by that point.
It measured fine, and it's a mesh full of crevices that's genuinely hard to see into. Ours cost about six dollars to replace, which was cheaper than thinking about it again.
Also measured fine. Also replaced. You can empty the crumb tray, but a toaster can't be fully cleaned inside, and it's the one piece of equipment that touches bread every single day.
Butter, cream cheese, jam, peanut butter, mayonnaise, hummus. A knife that's been on toast goes back into the tub, and that's all it takes. If the house isn't fully gluten free, this is the one to fix first: separate jars with a name on them, or squeeze bottles.
They move crumbs around the kitchen better than anything else you own.
Stainless steel, glass, and pure ceramic aren't porous. Those can be washed and shared, and a dishwasher handles them fine.
Flour is the one to actually worry about
If anyone in the house bakes with wheat flour, that matters more than anything else on this page. Flour thrown into a bowl hangs in the air for hours, reportedly 12 to 24 hours depending on the room, and then settles onto every surface, including the clean plate waiting for your child's lunch.
Everything else on this page is a shopping decision. This one is a decision about the house. We don't keep wheat flour at all. If you do keep it, the rule that helps is that it comes out when the celiac kid isn't about to eat, surfaces get wiped afterward, and nothing that's been sitting out gets used until it's been washed.
When gluten comes in the front door
A gluten-free kitchen still orders takeout. Chinese, subs, whatever the rest of the family wanted that night. That doesn't undo the kitchen, as long as it arrives the same way every time.
Paper plates and plastic forks, so none of it reaches the sink or the dishwasher. The table gets wiped down when everyone has finished. And the leftovers mostly don't go in the fridge, because a box of sub in there is a box somebody opens at eleven the next morning without thinking about it, and then the counter has been used.
Sushi is the one worth naming. Standard soy sauce is brewed with wheat, so the packets that come in the bag stay in the bag, and our own bottle of gluten-free tamari goes on the table instead. It's the same swap as at home, and it's easy to forget at a table covered in someone else's packaging.
Plenty of families run a shared kitchen and do it properly, and this page isn't an argument against that. We decided not to risk it. The other half of the decision had nothing to do with ppm: a child who is the only one in her own house eating differently is carrying it on her own. Taking the gluten out made it the household's diet instead of hers. In a house where somebody still eats gluten every day, the separate jars and the second toaster matter a great deal more than they do here.
20 ppm is the threshold a product has to be under to be labeled gluten free. It isn't a line below which nothing happens to a person. The review says so itself: few studies, controlled laboratory conditions, mostly one country, and results that varied with the method. A measurement from a lab is a useful fact, not permission. If your doctor or dietitian has told you to be stricter than this page, they know your child and this page doesn't.
This is background information and what has worked in one house. It isn't a diagnosis and it isn't medical advice. How strict your own kitchen needs to be is a question for your doctor or a dietitian.