I get this question at least twice a week from importers: “What material should I specify for my toilet seals?” Half of them don’t even know what EPDM or NBR stands for. That’s fine — they’re buyers, not chemists. But if you’re putting your company name on a product, you should at least know what it’s made of.
So here’s the real talk. No datasheets. No chemical diagrams. Just what matters.
EPDM is what you want 90% of the time. It handles heat, cold, ozone, UV. It’ll outlast the toilet it’s installed on. We’ve got EPDM seals that have been in place since the 1990s and still look new. The downside? It costs more than basic rubber — maybe 15 to 20 cents per unit at wholesale volume — but enough that cheap suppliers love to “accidentally” send you SBR instead.
SBR is the knockoff. Looks identical to EPDM. Feels the same. Costs half as much. Also crumbles after five to seven years. If your supplier can’t show you an EPDM material certification from their compound supplier, you’re getting SBR. I’ve seen it happen. A lot.
NBR is for when chemicals are involved. Hospitals, hotels, anywhere they’re dumping bleach tablets in the tank. Standard EPDM will degrade with bleach exposure. NBR won’t. It’s slightly less flexible than EPDM at extreme temperatures, but for indoor plumbing? Zero practical difference.
Silicone. The fancy option. Best temperature range, completely odorless, but tears easier than EPDM. We only recommend it for specialty applications.
My honest advice: specify EPDM, ask for the material cert, and don’t overthink it. If you have chemical exposure, go NBR. Skip silicone unless you have a very specific reason.