Drilling Countertop Holes for Faucet Installations

Important! Before you drill, be sure to check the underside of the sink so you won't be drilling into a brace or other obstruction that would make installation of the faucet difficult or impossible.

Faucets require a hole in the sink or countertop for installation.

Hole Sizing

• Faucet installation details will vary depending on the specific manufacturer and model, the following advice applies to our Tomlinson brand faucets and *most* of the generic RO and drinking water filter faucets we have encountered.

  Most standard (non-air-gap) faucets, with or without tubing attached, need a hole that's 7/8" in diameter to 1-1/8". You can install most standard faucets comfortably in holes up to 1-1/8".

Working with Existing Holes

• If you have an existing hole that's slightly larger, you'll need to find an oversized escutcheon to take up the slack. Try a local hardware or plumbing supply store.

• If you have an existing hole that's too small, there is no remedy other than to drill it larger. (We loaned our hole stretcher to a customer who did not return it.)

Drilling Through Steel, Porcelain or Cast Iron

• Drilling smaller holes in a stainless steel sink is usually quite easy. A 1/2" hole, for example, can be drilled with a standard metal bit from the hardware store. It's easiest to drill a small pilot hole, then follow with a 7/16" or 1/2" bit. The cone-shaped “Unibits” that drill an increasingly larger hole work great on stainless sinks. Larger holes are difficult in stainless. In hardware-store quality tools, a good sharp “hole saw” is your best choice.

• Many of the new sinks that appear to be porcelain are actually quite thin and quite easy to drill with a standard masonry drill bit. If in doubt, consult the sink manufacturer for advice.

• Drilling older porcelain or cast iron sinks should probably not be attempted unless you have special equipment (a Relton Sink Cutter, for example).