Bring water, salt, lemon juice, and butter to a simmer in a large pot over medium heat.
Meanwhile, trim about 1⁄2'' from the ends of white asparagus. Lay spears on a work surface, then peel thin skin from each with a sharp swivel-blade vegetable peeler, starting 1 1⁄2'' from the top and running the length of the spear. (Spears are brittle and can snap when peeled in midair.)
Gather spears into 2-4 bundles, tie loosely with kitchen string, and lower into simmering water. Cook, increasing heat to medium-high to maintain a simmer if necessary, until tender when pierced with the tip of a knife, 8-30 minutes, depending on thickness of asparagus. Lift bundles from simmering water with kitchen tongs and drain on paper towels.