Dishwasher Installation Plumbing Cost (2026 Guide)
💰 Cost Breakdown
| Item | Low | Average | High |
|---|---|---|---|
| Standard Replacement Hookup (Existing Plumbing) Disconnecting the old dishwasher and connecting the new one to existing hot water supply, drain, and electrical connections under the adjacent sink cabinet. Includes new braided stainless supply line, new drain hose if needed, and testing for leaks. This is the most common installation scenario when swapping an old dishwasher for a new one. | $150 | $250 | $400 |
| New Hot Water Supply Line (No Existing Hookup) Tapping into the existing hot water line under the kitchen sink and adding a dual-outlet shutoff valve (or a tee fitting with a dedicated valve) to supply the dishwasher. Includes running a braided stainless supply line from the valve through the cabinet wall to the dishwasher bay. | $100 | $175 | $275 |
| New Drain Connection Connecting the dishwasher drain hose to the kitchen sink tailpiece using a dishwasher tailpiece fitting, or to the knockout port on a garbage disposal. Includes installing a high loop under the countertop or an air gap device on the countertop or sink (code-dependent by jurisdiction). The high loop prevents backflow of dirty sink water into the dishwasher. | $75 | $125 | $200 |
| Air Gap Installation (Where Required by Code) A physical air gap device mounted on the sink or countertop that prevents drain backflow. Required by code in some states (California, Washington, Minnesota, and others) in addition to or instead of a high loop. Involves drilling a hole in the sink or countertop and running two hoses — one from the dishwasher to the air gap and one from the air gap to the disposal or drain. | $50 | $100 | $175 |
| Full New Rough-In (No Existing Plumbing) Complete plumbing rough-in for a dishwasher where none existed before. Includes hot water supply line with dedicated shutoff, drain connection with code-compliant backflow prevention, and potentially relocating or modifying existing sink plumbing to accommodate the dishwasher. Does not include electrical — that's a separate $150–$300 for an electrician to run a dedicated circuit. | $400 | $700 | $1,200 |
| Dishwasher Supply Line Kit (Parts Only) Braided stainless steel supply line, dual-outlet shutoff valve, Teflon tape, and compression fittings. This is the parts cost for DIY or what a plumber adds to the labor bill. | $15 | $30 | $50 |
Standard Replacement Hookup (Existing Plumbing)
Disconnecting the old dishwasher and connecting the new one to existing hot water supply, drain, and electrical connections under the adjacent sink cabinet. Includes new braided stainless supply line, new drain hose if needed, and testing for leaks. This is the most common installation scenario when swapping an old dishwasher for a new one.
New Hot Water Supply Line (No Existing Hookup)
Tapping into the existing hot water line under the kitchen sink and adding a dual-outlet shutoff valve (or a tee fitting with a dedicated valve) to supply the dishwasher. Includes running a braided stainless supply line from the valve through the cabinet wall to the dishwasher bay.
New Drain Connection
Connecting the dishwasher drain hose to the kitchen sink tailpiece using a dishwasher tailpiece fitting, or to the knockout port on a garbage disposal. Includes installing a high loop under the countertop or an air gap device on the countertop or sink (code-dependent by jurisdiction). The high loop prevents backflow of dirty sink water into the dishwasher.
Air Gap Installation (Where Required by Code)
A physical air gap device mounted on the sink or countertop that prevents drain backflow. Required by code in some states (California, Washington, Minnesota, and others) in addition to or instead of a high loop. Involves drilling a hole in the sink or countertop and running two hoses — one from the dishwasher to the air gap and one from the air gap to the disposal or drain.
Full New Rough-In (No Existing Plumbing)
Complete plumbing rough-in for a dishwasher where none existed before. Includes hot water supply line with dedicated shutoff, drain connection with code-compliant backflow prevention, and potentially relocating or modifying existing sink plumbing to accommodate the dishwasher. Does not include electrical — that's a separate $150–$300 for an electrician to run a dedicated circuit.
Dishwasher Supply Line Kit (Parts Only)
Braided stainless steel supply line, dual-outlet shutoff valve, Teflon tape, and compression fittings. This is the parts cost for DIY or what a plumber adds to the labor bill.
📊 Factors That Impact Cost
Existing Plumbing vs. New Rough-In
High ImpactReplacing a dishwasher where hookups already exist is a 1–2 hour job ($150–$400). Running new supply and drain lines where no dishwasher plumbing exists requires 3–5 hours and opening cabinet walls, which can triple the cost.
Local Code Requirements (Air Gap vs. High Loop)
Medium ImpactSome jurisdictions require only a high loop (free — just securing the drain hose at the underside of the counter). Others mandate a physical air gap device ($50–$175 installed), which requires drilling the sink or countertop and is a more involved install.
Distance From Sink
Medium ImpactThe dishwasher is typically installed directly adjacent to the sink for short plumbing runs. If it's positioned farther away (kitchen island installation or non-adjacent bay), longer supply and drain runs add $100–$300 in labor and materials.
Condition of Existing Shutoff Valves
Low ImpactIf the existing hot water shutoff valve under the sink is corroded, seized, or a gate valve (rather than a ball or quarter-turn valve), it should be replaced during the install. Add $50–$125 for a new valve. Discovering a bad shutoff during installation is common in homes over 20 years old.