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Cost to Add a Second Sink to a Bathroom

Adding a second sink to a bathroom means extending hot and cold water supply lines and the drain line, fitting a double vanity, and connecting faucets, waste fixtures, and P-traps for both basins. It is a hard plumbing modification: the cabinet must fit the room, the lines must reach the new location, and every connection must be checked for leaks.

Estimated cost
Add a second sink to a bathroom
$1,503
$1,005–$2,001
Labor
Materials
How many sinks?
Materials & supplies
  • Bathroom Sink Install Supplies (Drain Kit, P-trap, Supply Lines, Putty)1.1 each @ $75
    $82
  • Bathroom Sink Unit1.1 each @ $200
    $220
  • Plumbing Fittings and Supply Lines1.1 each @ $90
    $99
  • Supplies subtotal
    $280–$751
  • Labor
    $525–$1,050
  • Permits & fees
    $200

Based on 1 sink (typical size). Figures are ballparks — get a contractor quote to confirm.

Common reasons homeowners do this job

  • A bathroom upgrade calls for a double vanity and matching sinks.
  • An additional basin would make the bathroom work better for the household.
  • The existing vanity is worn or damaged.
  • The old vanity is being removed as part of a bathroom remodel.
  • The bathroom layout is being updated to accommodate a double vanity.

DIY or call a pro?

A licensed plumber should handle this work because it involves modifying water supply and drain lines. The main water supply should be turned off before plumbing work begins, and outlets near the new sink need GFCI protection. Check with your local building department whether this work needs a permit.

Frequently asked questions

Can I add a second bathroom sink myself, or should I hire someone?
A licensed plumber should do this job. Extending the hot and cold supply lines and the drain line requires plumbing modifications, and mistakes can cause water damage or problems with local requirements.
What makes the price of adding a second sink go up?
The price can rise with the job's size, labor time, and the materials selected, including the double vanity cabinet, sinks, faucets, P-traps, supply lines, and pipe fittings. Removing and disposing of the old vanity or material can also add to the work, while a small job may still involve a minimum or trip charge.
What should I check before choosing a double vanity?
Measure the bathroom first to confirm that the double vanity will fit. Also check whether the existing water supply and drain lines can be extended to the planned location of the second sink before selecting the cabinet and matching sinks.
What safety steps matter when adding the new sink plumbing?
Turn off the main water supply before any plumbing work starts. Outlets near the new sink should be GFCI protected, and all supply-line and drain-pipe connections should be checked for leaks after the water is turned back on.

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