Water on a floor drain after a closed night means one of two things: equipment kept discharging, or wastewater arrived from somewhere else. Check whether it is clean water or sewage, what was running, and whether neighbors or the city main are affected. Nothing running inside points to a shared or downstream blockage.
Is it clean water or sewage?
Look, smell and test the trend. Clean, odorless water that is not rising points to equipment. Gray or dark water, debris, paper or a sewer smell points to a backup. If it is sewage, keep people out of the area and stop water use in the building.
Equipment that discharges overnight
Some equipment keeps draining while you are closed:
- Ice machines. Hoshizaki's manual warns that "If the ice storage bin drain becomes clogged, water could build up in the bin and overflow." A machine that keeps making ice overnight can overflow onto the floor and into the nearest drain.
- Water softeners and RO systems that regenerate or flush at night. Softener drain backup during regeneration covers that.
- Walk-in condensate and other indirect drains that discharge to a floor sink.
If the drain line from a machine is the problem, the water appears at the drain it empties into. See floor drain backing up for what to try first.
Wastewater from somewhere else
If nothing inside was running, a sewage backup came from upstream. Phoenix's FOG manual describes the mechanism: "When a blockage occurs, the sewage coming from upstream backs up and finds another way out. It could exit through a manhole then run down the street or through a drain or clean out in your home or business." The lowest opening in a building usually shows it first, and that is often a floor drain.
EPA lists the usual causes of sewer overflows: "blockages, line breaks, sewer defects that allow stormwater and groundwater to overload the system, power failures, improper sewer design, and vandalism." In a strip center or multi-tenant building, a neighbor's discharge can raise the water in a shared line while your unit sits empty. Sewer smell in a strip mall with a shared line covers shared lines, and a sewer backup in a multi-tenant building lays out the first steps for managers.
What to do first
- 1Do not run water, flush or use the dish machine.
- 2Photograph the drain and the floor from a safe spot.
- 3Ask neighbors and the property manager whether they see the same thing.
- 4Call a commercial plumber to find the blockage. If it is in the city's main, the city has to be told.
We run emergency calls 24/7, camera the line and jet it when the blockage is on your side, and quote the price up front.