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Community and Q&A

Overflow drain on sink

user-6184358 | Posted in General Questions on

Having recently installed a kitchen sink & bathroom sink – Why is there overflow protection on the bathroom sink and not on the kitchen sink?

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  1. JC72 | | #1

    Traditionally bathrooms are located on an upstairs floor so you want to prohibit flooding which would damage not only the upstairs floor but the ceiling and floor in the living area below. Kitchens are typically located on ground floors so flooding isn't much of an issue. In addition the comparatively large size of the kitchen sink means it's less likely to fill up and overflow while unattended.

    Laundry sinks don't have overflows either but they were typically placed in the basement and nobody cared if the basement flooded.

  2. Expert Member

    I think it's also behavioural. Bathroom sinks are more likely to be used by children, and tubs are often left unattended while they fill.

    Most double kitchen sinks have overflow protection of a sort. The divider between them is typically a bit lower than the rim, so one side can drain to the other.

  3. Trevor_Lambert | | #3

    There is no hard and fast rule, either. My kitchen sink (Blanco Metra) has an overflow, and the bathroom sink I just bought does not.

    Malcom, there are definitely lots of double kitchen sinks with with a lowered divider, but the most common ones does not. That drain method also doesn't work if the plug is in the other one.

    1. Expert Member
      MALCOLM TAYLOR | | #4


      I can't find a drop-in double sink in the Lowes catalogue that doesn't have a lowered divider. The under-mounts don't but the counter forms a lip all round.

      I think most European kitchen sinks have overflows. I know those in England do. Maybe that's the distinction?

      1. Trevor_Lambert | | #5

        They are more common now, but if you count all the sinks out there still in use, the ones without a lowered divider would be the vast majority. There used to be almost a standard stainless double sink, that seemingly every house had. Similar to this:

  4. Expert Member

    True. That looks just like the one we had growing up.

    Whenever I've removed an old bathroom sink the overflow has been almost completely blocked. I wonder how many would work if you left the taps on full?

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