How much does it cost to add a second sink to a vanity?

The cost to convert single sink vanity to double sink depends on whether you can reuse the cabinet and countertop, and how much plumbing must change; get an installed quote for the complete scope rather than treating it as a sink purchase. For your 2026 remodel, include removal, faucet connections, drainage, countertop work and any wall repairs in that quote.

Why this matters

A second basin changes more than the countertop. You need room for another faucet, drain assembly and working position without sacrificing access to drawers or crowding the bathroom doorway.

Start with the cabinet interior and existing pipe locations. The bathroom vanity plumbing hookup workflow covers the connections to review before you commit to a layout. Choose the installation approach before choosing the finish.

How much does it cost to add a second sink to a vanity?

Your installed total combines the fixtures, cabinet or countertop work, plumbing changes and finishing work. A usable 2026 estimate separates those categories and states what the installer will reuse.

Ask for this breakdown rather than a single unexplained total:

Quote category	What the scope should identify	What to clarify
Cabinet	Retain, modify or replace the existing base	Whether drawers and structural parts remain usable
Countertop and sinks	Fabricate a replacement top or assess the existing one	Basin locations, faucet holes and sink mounting
Faucets and drains	Supply and install the specified fixtures	Which connection parts are included
Plumbing	Connect both sinks to an approved arrangement	Whether walls must open or pipes must move
Installation	Remove the old unit and set the new components	Who handles disposal and final testing
Finishing	Repair surfaces disturbed by the work	Whether painting, trim and backsplash work are included

A quote for adding a basin to an existing cabinet is not directly comparable with a quote for replacing the entire vanity. Make both installers describe the finished result, including functional drawers, accessible shutoffs and tested connections.

Also establish who supplies each component. A homeowner-supplied faucet still needs installation, and an included sink does not mean the bathroom's existing plumbing is ready for it.

Retain the cabinet: best for a compatible existing layout

Keeping your cabinet is worth evaluating when its condition, interior layout and dimensions suit two sinks. The benefit is retaining a base you already like; the limitation is working around its existing partitions, drawers and plumbing openings.

Have the installer inspect the cabinet before you order a top. A wide exterior does not prove that another basin and drain will fit inside, especially when a central drawer stack occupies the proposed sink location.

The countertop needs a separate assessment. Adding a cutout is not simply a matter of finding an empty patch: the fabricator must assess the material, remaining support and spacing around existing openings.

Best for: homeowners whose cabinet passes both the plumbing and countertop assessments. Skip this approach if making room for the second sink requires compromising the cabinet's structure or essential storage.

Replace the vanity: best for changing the sink layout

A complete double-sink vanity gives you a cabinet and top designed around two basins. That removes the need to adapt a single-sink countertop, but it does not eliminate plumbing or installation work.

Compare these two Eviva double-sink vanities by verified layout details rather than assuming that a wider unit automatically fits better:

Option	Verified configuration	Best for	Trade-off to assess
London 48-inch white double-sink vanity	48-inch width, Carrara quartz top, undermount porcelain sinks	A replacement plan requiring a 48-inch double-sink unit	Check usable counter space and the distance between working positions
Lugano 72-inch natural oak wall-mount double-sink vanity	72-inch width, wall mounting, acrylic top and integrated sinks	A wider layout planned around a wall-mounted installation	Confirm wall support and compatibility with existing pipe locations

Eviva double-sink vanities are best for homeowners replacing the cabinet and top as a coordinated unit. Neither configuration is a shortcut around measuring the room or confirming plumbing fit.

For a 2026 purchase, verify the current installation documentation before ordering. Match the selected model's actual dimensions and openings to your bathroom rather than relying on the width in its name alone.

How width changes your conversion plan

48-inch double-sink layouts: check the working positions

A 48-inch double-sink vanity is a real product configuration, not proof that every 48-inch cabinet can accept another sink. The basin placement, faucet locations and cabinet interior must work together.

Mark both standing positions on the floor before ordering. Open the nearby door and imagine reaching for towels, toiletries and drawers while someone uses the other basin.

60-inch layouts: inspect inside the cabinet

A 60-inch vanity gives you another width to evaluate, but the measurement alone does not settle conversion feasibility. A single-sink cabinet's internal storage arrangement still determines where another basin and drain can go.

For Eviva options in this width, compare the specified sink configuration rather than treating single- and double-sink versions as interchangeable. Request the drawing for the exact model you intend to buy.

72-inch double-sink layouts: include installation fit

A 72-inch double-sink unit needs an appropriate wall location and a workable route into the bathroom. Measure the access path as well as the destination, including turns and door openings.

For wall-mounted models, make support part of the installation plan before the wall is finished. A wider cabinet is only an improvement when the room, wall and plumbing support the layout.

Why the conversion scope varies

The difference between projects comes from what must change, not just which sink you select. Keep these factors visible when reviewing your 2026 quotes:

• Cabinet compatibility: partitions, drawers and existing damage affect whether reuse makes sense.
• Countertop compatibility: material, cutout locations and support determine the fabrication approach.
• Pipe locations: the proposed basins must connect to suitable water supplies and drainage.
• Installation type: a wall-mounted replacement needs a support plan suited to its instructions.
• Disturbed finishes: moving or removing the vanity can expose surfaces that need repair.
• Fixture fit: faucet mounting and drain components must match the selected top and sinks.

Ask each contractor to distinguish confirmed work from work that depends on opening the wall. That makes the estimate easier to compare and gives you a clear process for approving changes.

Confirm the plumbing plan before you order

Adding another faucet requires suitable hot- and cold-water connections, while another basin requires a compliant drainage arrangement. These are related tasks, but they are not the same task.

A plumber should assess the existing drain, venting and supply arrangement against the proposed layout and local requirements. Do not assume an extra branch fitting is the complete solution simply because both basins sit above the same cabinet.

The distinction between extending nearby supplies and installing new pipe runs also matters when discussing new water line installation costs. Ask your US installer to identify which work your bathroom needs; a whole-house piping scope is not a direct comparison for a vanity connection.

Before approving plumbing work, request clear answers to these questions:

• Will the proposed drain arrangement work with the existing venting?
• Do the pipes conflict with drawers or cabinet mounting points?
• Can you reach the shutoff valves after installation?
• Will any wall or floor surfaces need opening?
• Who handles required permits, inspections and finish repairs?

Confirm the drain arrangement before buying the vanity. Discovering a conflict after delivery leaves you choosing between changing the plumbing and changing the cabinet.

Compare quotes using the same finished result

For your 2026 remodel, send each installer the same proposed layout and product documentation. Include photographs of the existing cabinet interior, pipe locations and surrounding walls so the initial discussion addresses the actual bathroom.

Ask for separate scopes for cabinet reuse and complete replacement when both are feasible. The reuse proposal should identify any countertop fabrication and cabinet changes; the replacement proposal should identify removal, setting, connection and finishing work.

Keep responsibility clear. If you supply the vanity, establish who checks the delivered components against the installation plan before demolition begins.

Use this sequence when comparing proposals:

1. Confirm the layout. Both quotes should describe the same sink count and intended cabinet location.
2. Match the included work. Check removal, disposal, plumbing connections, testing and surface repairs.
3. Identify exclusions. Separate optional design changes from work necessary for a functioning installation.
4. Set a change process. Require approval before concealed conditions lead to additional work.

Do not choose between proposals until you can explain why their scopes differ. A shorter scope can leave more work for you to arrange separately.

Can you keep your existing countertop when adding a second sink?

You can keep the existing countertop only if a fabricator confirms that the material, cutout positions and remaining support allow the change. Available surface area alone is not enough.

Have the fabricator assess the sink and faucet openings together. Replacing the top is the alternative when the existing layout cannot accommodate the proposed basins without an unsuitable modification.

Is replacing the vanity better than converting it?

Replacing the vanity is the better fit when the existing cabinet or top cannot accommodate two sinks without substantial alterations. Converting remains worth considering when the base is sound and the revised layout works.

Compare both approaches as completed installations, not as isolated purchases. Include the storage you retain or lose, as well as the work needed to make each approach functional.

FAQ

One last thing

Test the storage layout before committing to another basin. The second sink occupies space below the countertop as well as above it, so a conversion can change where you keep everyday items.

Draw the proposed basins and plumbing zones onto a cabinet plan, then assign places for the things you actually store. If the result solves the morning queue but removes essential storage, reconsider the cabinet configuration before ordering.

Related guides

• How much clearance do you need for a double-sink vanity?
• How to connect a double-sink vanity to shared drain lines