Plumbing that was fitted in, not planned

When a basement bathroom goes into a house from the 1920s, the installer has to work with what is there: a slab that may be thin or uneven, a main drain that leaves the house at a fixed height, and supply lines running overhead through old joists. Depending on that height, the toilet and shower may drain by gravity into the existing line through trenches cut into the slab, or they may drain into a sealed pit with a sewage ejector pump that lifts waste up to the main.

Both setups work, but each has typical weak points. Trenched drains can settle or leak at new-to-old connections under the slab. Shower pans in basement showers sit right on concrete and can fail without obvious signs until baseboards in the next room swell. Ejector pumps depend on electricity, a working float switch and a check valve; when any of them fails, waste backs up into the shower or floor.

Remodels done in stages make it harder to know what you have. A bathroom installed in the 1980s and refreshed in the 2010s may have new tile over old supply lines, or a vanity connected with braided hoses that are now well past their expected life.

Where basement bathrooms usually leak

Location
Shower pan or tile
What it looks like
Damp carpet or swollen baseboard in the room next to the shower
Who to call first
A plumber or tile contractor to test the pan
Location
Toilet wax ring
What it looks like
Water or stains around the toilet base, odor
Who to call first
A plumber; the subfloor here is concrete, so damage spreads sideways
Location
Vanity supply hoses
What it looks like
Water inside the vanity cabinet or on the floor in front
Who to call first
Shut the angle stops, then a plumber
Location
Ejector pump or pit
What it looks like
Sewage in the shower or around the pit lid, alarm sounding
Who to call first
A plumber familiar with ejector systems; treat as sewage
Location
Drain line under slab
What it looks like
Persistent dampness at one area of slab with no visible source
Who to call first
A plumber with leak detection or camera equipment

What to do when you find water near the bathroom

  1. Find the shutoffs

    Close the angle stops under the sink and behind the toilet. If you cannot find the source, close the main shutoff, often near where the water line enters through the front foundation wall.

  2. Check the ejector

    If there is a pit, listen for the pump and look for a tripped breaker or alarm. Do not use any fixture that drains into it until it is working.

  3. Pull back flooring at the edges

    Lift carpet corners or remove a baseboard to see how far water spread beyond the bathroom.

  4. Record readings and photos

    Even simple photos with a tape measure show the spread. Moisture readings from a restorer add detail for insurers.

  5. Fix the source before drying

    Drying a room while a shower pan still leaks only delays the next round of damage.

Questions for the plumber

  1. Does this bathroom drain by gravity or through an ejector, and what condition is it in?
  2. Is the check valve on the ejector discharge working?
  3. Was the shower pan installed with a membrane, and how can it be tested?
  4. Are the supply lines and hoses original to this remodel, and should they be replaced now?
  5. Would a high-water alarm or automatic shutoff make sense here?

General information for Washington Park, not a quote or professional advice. In an emergency, call 911.