Combine carrots, water, onion, cider vinegar, salt, sugar, peppercorns, and bay leaves in a saucepan; bring to a boil. Reduce heat; simmer until sugar and salt dissolve, about 2 minutes. Pour over jalapenos and cover with a plate to keep vegetables submerged. Cool for about 1 hour.

Place jalapenos in a large bowl. Pour carrot mixture over jalapenos and cover with a plate to keep vegetables submerged. Let sit until for flavors to blend, about 1 hour. Discard bay leaves. pour the mixture in a glass jar and cover; refrigerate.