Spot the Violation

PlumbingWater supply & distributionLevel 32018 UPC

Sink base with dishwasher hookup

Open kitchen sink base cabinet under a double-bowl stainless sink. Red PEX for hot water rises through the cabinet floor at the left and blue PEX for cold at the right; each ends in a chrome straight stop with an oval handle and a braided stainless riser up to the faucet. On the red line, below its stop, a brass PEX tee sends a branch sideways to a braided stainless dishwasher connector that loops across the cabinet floor and through a hole in the left side panel. A gray corrugated dishwasher drain hose comes through the same panel and rises to an air gap body under the countertop, with a second hose down to a branch tailpiece on the left bowl. A white PVC P-trap and continuous waste run to the wall, and a bucket and dish soap sit on the cabinet floor.
Kitchen sink base, new dishwasher installed to the left

What's wrong here?

  1. The dishwasher branch tees off the hot line ahead of the stop, so the dishwasher has no control valve of its own
  2. A dishwasher must be supplied from the cold line
  3. Braided stainless connectors may not be used for a faucet or a dishwasher
  4. Nothing. This installation is compliant
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Show the answer and the code reference

The answer

The dishwasher connector is fed from a tee on the hot PEX below the faucet stop, with no valve of its own, so the appliance cannot be shut off at the sink.

Correct choice: 1. The dishwasher branch tees off the hot line ahead of the stop, so the dishwasher has no control valve of its own

UPC 606.5 requires a control valve immediately ahead of each water-supplied appliance and immediately ahead of each slip-joint or appliance supply. The faucet has its stops, but the tee for the dishwasher sits on the supply side of the hot stop, so closing that stop does nothing for the dishwasher. When the dishwasher's inlet valve or connector fails, or the machine has to be pulled for service, the only way to stop the water is the main or the water heater shutoff. This one is easy to miss at final because the cabinet looks finished and every stop has a handle.

How to fix it

Replace the hot stop with a dual-outlet (faucet and dishwasher) stop, or put a separate 1/4-turn stop on the dishwasher branch right after the tee, so the dishwasher connector starts at a valve.

Code reference

  • UPC 2018 606.5 — Control Valve

    A control valve is to be installed immediately ahead of each water-supplied appliance and immediately ahead of each slip-joint or appliance supply. Parallel (manifold) water distribution systems may put the control valve at the manifold, identified with the fixture served, instead of at the fixture.

    Drills citing 606.5

Minnesota

MN adopts this rule as writtenConfidence: medium

Minnesota adopts the 2018 Uniform Plumbing Code with Minnesota amendments as the Minnesota Plumbing Code (Minn. Rules ch. 4714, effective Dec. 17, 2021). No Minnesota amendment to 606.5 is known; check ch. 4714 before relying on it.

About the Minnesota Plumbing Code

Why the other choices are wrong

  • A dishwasher must be supplied from the cold line. Residential dishwashers are normally connected to hot water; the manufacturer's instructions call for it. Which line it is on is not the problem.
  • Braided stainless connectors may not be used for a faucet or a dishwasher. Listed flexible water connectors are permitted where they stay accessible, as they are in an open sink base.
  • Nothing. This installation is compliant. Closing the hot stop shuts off the faucet but not the dishwasher. The dishwasher line can only be isolated by shutting off the whole house or the water heater.
Code complianceLevel 3 · Master#shutoff#control valve#stop valve#dishwasher#kitchen#PEX

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