Spot the Violation

PlumbingBackflow & cross-connectionsLevel 12018 UPC

Basement laundry tub

Unfinished basement laundry corner. A freestanding white plastic laundry tub on four legs is filled most of the way with gray, soapy water, and a work shirt is soaking in it. A two-handle chrome utility faucet sits on the back ledge of the tub; its swing spout ends in plain male hose threads, and a green garden hose is screwed onto it. The hose drops into the tub and coils along the bottom under the water. A white PVC P-trap runs from the tub drain to a vertical PVC drain pipe beside the tub. To the right, a top-load washer stands under a recessed washer box with hot and cold valves and a standpipe opening. A jug of detergent sits on the floor at left.
Basement laundry room, utility tub and washer

What's wrong here?

  1. The hose-thread spout on the tub faucet has no vacuum breaker, and the hose end sits under the water in the tub
  2. The washer box valves need hose-connection vacuum breakers
  3. A laundry tub may not drain through a P-trap; it must spill into the floor drain
  4. Nothing. This installation is compliant
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Show the answer and the code reference

The answer

The utility faucet has a hose-thread spout with no vacuum breaker, and the hose connected to it lies below the water in the tub, creating a submerged inlet.

Correct choice: 1. The hose-thread spout on the tub faucet has no vacuum breaker, and the hose end sits under the water in the tub

UPC 603.5.7 requires every potable water outlet with a hose attachment, other than water heater drains, boiler drains and clothes washer connections, to be protected by a nonremovable hose bibb-type vacuum breaker or backflow preventer, or by an atmospheric vacuum breaker at least 6 in. above the highest point of use. This faucet has plain hose threads and no device. With the hose end lying in a tub of wash water, any drop in supply pressure (a main break, a hydrant flush, someone opening a big valve upstairs) can siphon that water back into the cold and hot lines. UPC 603.1 requires cross-connection control for exactly this situation.

How to fix it

Install a nonremovable hose-connection vacuum breaker on the spout threads (the type with a breakaway set screw), or replace the faucet with a utility faucet that has an integral vacuum breaker. Pull the hose out of the water; it should hang above the tub's flood rim.

Code references

  • UPC 2018 603.5.7 — Outlets with Hose Attachments

    Potable water outlets with hose attachments, other than water heater drains, boiler drains and clothes washer connections, must be protected by a nonremovable hose bibb-type backflow preventer, a nonremovable hose bibb-type vacuum breaker, or an atmospheric vacuum breaker installed at least 6 in. above the highest point of usage on the discharge side of the last valve.

    Drills citing 603.5.7

  • UPC 2018 603.1 — General

    Cross-connection control must be provided in accordance with Chapter 6. Equipment, mechanisms or substances that could pollute or contaminate the potable water supply are permitted only where the supply is protected by an approved backflow prevention device or assembly.

    Drills citing 603.1

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). Minnesota amends parts of UPC section 603 (reportedly in Minn. Rules 4714.0603), but no Minnesota amendment to 603.5.7 is known; check ch. 4714 before relying on it.

About the Minnesota Plumbing Code

Why the other choices are wrong

  • The washer box valves need hose-connection vacuum breakers. UPC 603.5.7 specifically exempts clothes washer connections from the hose-outlet vacuum breaker rule; the washer's own fill valve and air gap protect that connection.
  • A laundry tub may not drain through a P-trap; it must spill into the floor drain. A laundry tub is a fixture and is trapped and vented like any other. Indirect waste to a floor drain is for things like water softener and condensate discharge, not a laundry tub.
  • Nothing. This installation is compliant. Any potable outlet with hose threads (other than washer, water heater and boiler drain connections) needs a nonremovable hose-type vacuum breaker or backflow preventer, and here the hose is a submerged inlet sitting in dirty water.
Safety hazardLevel 1 · Apprentice#vacuum breaker#hose connection#submerged inlet#laundry tub#backsiphonage#basement

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